docs: update for Python 3.12

Use "r" (raw) strings for the regexp.

Signed-off-by: Jeff Squyres <[email protected]>

docs/conf.py

@@ -242,7 +242,7 @@ def _doit(topdir):
         for root, dirs, files in os.walk(topdir):
             for filename in files:
                 # Parse filenames of the format a "foo.X.rst"
-                parts = re.search("^([^/]+?)\.([0-9]+)\.rst$", filename)
+                parts = re.search(r"^([^/]+?)\.([0-9]+)\.rst$", filename)
 
                 # Skip files that do not match that format (e.g.,
                 # "index.rst")