require rtd theme < 3.0.0

Author: clonker

docs/requirements.txt

@@ -1,7 +1,8 @@
 # Older versions of sphinx-rtd-theme do not work with never docutils but have a bug in the dependency
 # which could result in it being installed anyway and the style (especially bullet points) being broken.
 # See https://github.com/readthedocs/sphinx_rtd_theme/issues/1115
-sphinx_rtd_theme>=0.5.2
+# theme >=3.0.0 removes the display_version option in favor of version_selector and language_selector
+sphinx_rtd_theme>=0.5.2, <3.0.0
 
 pygments-lexer-solidity>=0.7.0
 sphinx-a4doc>=1.6.0; python_version < '3.13'