Constrain python-docs-theme to version 2023.3.1 or older

Author: AA-Turner

build_docs.py

@@ -200,6 +200,7 @@ def requirements(self) -> list[str]:
             "docutils<=0.17.1",
             "jieba",
             "jinja2<3.1",
+            "python-docs-theme<=2023.3.1",
             "sphinxcontrib-applehelp<=1.0.2",
             "sphinxcontrib-devhelp<=1.0.2",
             "sphinxcontrib-htmlhelp<=2.0",