Unify OTIO versions, pin to 0.18.1 (#982)

### Pin OTIO to 0.18.1

### Summarize your change.
Currently OTIO is 0.16 on Window debug and the latest main branch for
everything else. This branch does two things:
- unify the version between all OSes
- pin the version to 0.18.1.

Windows debug builds the OTIO wheel from source since there are no
pre-built debug Windows wheels available in pypi, and we can't use the
release one since Windows doesn't allow mixing release and debug
libraries. As a result, it's version was specified outside of the
requirements.txt file we use for everything else to install from pypi.
It's version was far behind the other OSes likely because whenever we
updated it, we thought doing so in a single place would take care of
everything.

To remove the chance of this happening again, I removed the
requirements.txt file we use for installing our python build
dependencies and instead auto-generated it from a template, using the
opentimelineio version as an input variable from CMake so the version is
now shared between all builds.

Lastly, I pinned the OTIO version to 0.18.1 which was just released this
week. It's risky to use the latest main branch since one bad commit
could break OpenRV.

### Describe the reason for the change.

Build stability and consistency.

### Describe what you have tested and on which operating system.

Building on  Windows + Linux

---------

Signed-off-by: Roger Nelson <[email protected]>

Author: rogernelson

cmake/dependencies/python3.cmake

@@ -33,8 +33,12 @@ SET(RV_DEPS_PYTHON_VERSION_SHORT
     "${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR}"
 )
 
+# This version is used for:
+# 1. Building OpenTimelineIO from source for Windows debug builds
+# 2. Generating src/build/requirements.txt from requirements.txt.in template
+#    (used by all other platforms/builds to install from PyPI)
 SET(_opentimelineio_version
-    "0.16.0"
+    "0.18.1"
 )
 
 RV_VFX_SET_VARIABLE(_pyside_version CY2023 "5.15.10" CY2024 "6.5.3")
@@ -249,8 +253,18 @@ ELSE() # Not WINDOWS
   )
 ENDIF()
 
-SET(_requirements_file
-    "${PROJECT_SOURCE_DIR}/src/build/requirements.txt"
+# Generate requirements.txt from template with the OpenTimelineIO version substituted
+SET(_requirements_input_file
+    "${PROJECT_SOURCE_DIR}/src/build/requirements.txt.in"
+)
+SET(_requirements_output_file
+    "${CMAKE_BINARY_DIR}/requirements.txt"
+)
+
+CONFIGURE_FILE(
+    ${_requirements_input_file}
+    ${_requirements_output_file}
+    @ONLY
 )
 
 IF(RV_TARGET_WINDOWS)
@@ -269,18 +283,18 @@ IF(RV_TARGET_WINDOWS)
         ${CMAKE_COMMAND} -E env
         "OTIO_CXX_DEBUG_BUILD=1"
         "CMAKE_ARGS=-DPYTHON_LIBRARY=${_python3_implib} -DPYTHON_INCLUDE_DIR=${_include_dir} -DPYTHON_EXECUTABLE=${_python3_executable}"
-        "${_python3_executable}" -m pip install --upgrade -r "${_requirements_file}"
+        "${_python3_executable}" -m pip install --upgrade -r "${_requirements_output_file}"
     )
   ELSE()
     SET(_requirements_install_command
         ${CMAKE_COMMAND} -E env
         "CMAKE_ARGS=-DPYTHON_LIBRARY=${_python3_implib} -DPYTHON_INCLUDE_DIR=${_include_dir} -DPYTHON_EXECUTABLE=${_python3_executable}"
-        "${_python3_executable}" -m pip install --upgrade -r "${_requirements_file}"
+        "${_python3_executable}" -m pip install --upgrade -r "${_requirements_output_file}"
     )
   ENDIF()
 ELSE()
   SET(_requirements_install_command
-      "${_python3_executable}" -m pip install --upgrade -r "${_requirements_file}"
+      "${_python3_executable}" -m pip install --upgrade -r "${_requirements_output_file}"
   )
 ENDIF()
 
@@ -359,11 +373,11 @@ SET(${_python3_target}-requirements-flag
 )
 
 ADD_CUSTOM_COMMAND(
-  COMMENT "Installing requirements from ${_requirements_file}"
+  COMMENT "Installing requirements from ${_requirements_output_file}"
   OUTPUT ${${_python3_target}-requirements-flag}
   COMMAND ${_requirements_install_command}
   COMMAND cmake -E touch ${${_python3_target}-requirements-flag}
-  DEPENDS ${_python3_target} ${_requirements_file}
+  DEPENDS ${_python3_target} ${_requirements_output_file} ${_requirements_input_file}
 )
 
 IF(RV_TARGET_WINDOWS
@@ -375,7 +389,7 @@ IF(RV_TARGET_WINDOWS
     POST_BUILD
     COMMENT "Copying Debug Python lib as a unversionned file for Debug"
     COMMAND cmake -E copy_if_different ${_python3_implib} ${_python_release_libpath}
-    COMMAND cmake -E copy_if_different ${_python3_implib} ${_python_release_in_bin_libpath} DEPENDS ${_python3_target} ${_requirements_file}
+    COMMAND cmake -E copy_if_different ${_python3_implib} ${_python_release_in_bin_libpath} DEPENDS ${_python3_target} ${_requirements_output_file} ${_requirements_input_file}
   )
 ENDIF()
 

src/build/requirements.txt renamed to src/build/requirements.txt.in

@@ -1,10 +1,10 @@
 # This file contains all the packages that will be packaged with RV. Please add the license next to the package.
+# NOTE: This is a CMake template file. The actual requirements.txt is generated during CMake configuration.
+#       To update OpenTimelineIO version, edit _opentimelineio_version in cmake/dependencies/python3.cmake
 
 pip                     # License: MIT License (MIT)
 setuptools              # License: MIT License
-# We need to use the main branch of the OTIO Github repo since the latest release available as a Pypi package is missing some features we need for Live Review
-# Using the latest from main branch.
-git+https://github.com/AcademySoftwareFoundation/OpenTimelineIO@main#egg=OpenTimelineIO # License: Other/Proprietary License (Modified Apache 2.0 License)
+OpenTimelineIO==@_opentimelineio_version@ # License: Other/Proprietary License (Modified Apache 2.0 License)
 PyOpenGL                # License: BSD License (BSD)
 
 # MacOS only - PyOpenGL_accelerate is built from source in python3.cmake as a workaround until the fix
@@ -24,3 +24,4 @@ packaging               # License: Apache Software License, BSD License
 requests                # License: Apache Software License (Apache 2.0)
 cryptography            # License: Apache Software License, BSD License ((Apache-2.0 OR BSD-3-Clause) AND PSF-2.0)
 pydantic                # License: MIT License (MIT)
+