Pin sphinx_rst_theme to < 3.0 for docs (#3597)

Author: yvonnefroehlich

.github/workflows/ci_docs.yml

@@ -115,7 +115,7 @@ jobs:
             sphinx-copybutton
             sphinx-design
             sphinx-gallery
-            sphinx_rtd_theme
+            sphinx_rtd_theme<3.0
 
       # Download cached remote files (artifacts) from GitHub
       - name: Download remote data from GitHub

ci/requirements/docs.yml

@@ -30,4 +30,4 @@ dependencies:
     - sphinx-copybutton
     - sphinx-design
     - sphinx-gallery
-    - sphinx_rtd_theme
+    - sphinx_rtd_theme<3.0

environment.yml

@@ -42,7 +42,7 @@ dependencies:
     - sphinx-copybutton
     - sphinx-design
     - sphinx-gallery>=0.17.0
-    - sphinx_rtd_theme
+    - sphinx_rtd_theme<3.0
     # Dev dependencies (type hints)
     - mypy
     - pandas-stubs