[CMake Examples] Update required CMake versions (#384)

Author: tyler-yankee

drake_cmake_external/CMakeLists.txt

@@ -3,7 +3,9 @@
 # TODO(eric.cousineau): Link to documentation on superproject example pending
 # resolution of: https://gitlab.kitware.com/cmake/cmake/issues/18336
 
-cmake_minimum_required(VERSION 3.16)
+# See https://drake.mit.edu/from_source.html for the versions of CMake
+# officially supported by Drake when building from source.
+cmake_minimum_required(VERSION 3.22...4.0)
 project(drake_cmake_external)
 
 if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)

drake_cmake_installed/CMakeLists.txt

@@ -1,6 +1,11 @@
 # SPDX-License-Identifier: MIT-0
 
-cmake_minimum_required(VERSION 3.16)
+# Note that the minimum required version of CMake to consume a binary
+# installation of Drake is lower than the minimum required version
+# when building Drake from source (as seen in drake_cmake_external).
+# The maximum version below allows for the use of modern policies
+# with newer versions of CMake.
+cmake_minimum_required(VERSION 3.9...4.0)
 project(drake_cmake_installed)
 
 # N.B. This is a temporary flag. It only really applies to Linux, as Mac

drake_cmake_installed_apt/CMakeLists.txt

@@ -1,6 +1,11 @@
 # SPDX-License-Identifier: MIT-0
 
-cmake_minimum_required(VERSION 3.16)
+# Note that the minimum required version of CMake to consume a binary
+# installation of Drake is lower than the minimum required version
+# when building Drake from source (as seen in drake_cmake_external).
+# The maximum version below allows for the use of modern policies
+# with newer versions of CMake.
+cmake_minimum_required(VERSION 3.9...4.0)
 project(drake_cmake_installed_apt)
 
 include(CTest)