DOCS: fix readthedocs build

Author: Puerling

.readthedocs.yaml

@@ -9,13 +9,15 @@ version: 2
 build:
   os: ubuntu-24.04
   tools:
-    python: "3.12"
+    python: "mambaforge-23.11"
+  jobs:
+    pre_create_environment:
+      - conda update --yes --quiet --name=base --channel=conda-forge conda
 
 # Build documentation in the "docs/" directory with Sphinx
 sphinx:
   configuration: conf.py
 
 
-python:
-  install:
-    - requirements: docs/requirements.txt
+conda:
+  environment: docs/environment.yml

conf.py

@@ -242,6 +242,9 @@
     }
 ]
 
+# This allows skipping the build process because the object library is never required
+autodoc_mock_imports = ["spirit.spiritlib"]
+
 
 def pre_build_hook(_):
     """
@@ -256,8 +259,8 @@ def pre_build_hook(_):
     subprocess.check_call(
         [
             "cmake",
-            "-B build",
-            "-S .",
+            "-B", "build",
+            "-S",  ".",
             "-DSPIRIT_BUILD_FOR_CXX=OFF",
             "-DSPIRIT_BUILD_TEST=ON",
             "-DSPIRIT_SKIP_HTST=ON",

docs/environment.yml

@@ -0,0 +1,16 @@
+---
+name: RTD
+channels:
+  - nodefaults
+  - conda-forge
+dependencies:
+  - python>=3.11
+  - pandoc
+  - sphinx>=8.2
+  - sphinx_rtd_theme
+  - sphinx-markdown-tables
+  - myst-parser
+  - doxygen
+  - breathe
+  - numpy
+  - cmake>=3.20