Handle cases when Any is not an instance of type

This is only needed for Python 3.10 and earlier.

Author: AA-Turner

CHANGES.rst

@@ -4,6 +4,8 @@ Release 7.3.4 (in development)
 Bugs fixed
 ----------
 
+* Handle cases when ``Any`` is not an instance of ``type``.
+  Patch by Adam Turner.
 
 Release 7.3.3 (released Apr 17, 2024)
 =====================================

sphinx/config.py

@@ -532,7 +532,7 @@ def _validate_valid_types(
         return ()
     if isinstance(valid_types, (frozenset, ENUM)):
         return valid_types
-    if isinstance(valid_types, type):
+    if isinstance(valid_types, type) or valid_types is Any:
         return frozenset((valid_types,))
     if isinstance(valid_types, set):
         return frozenset(valid_types)