DOC: fix build failure with sphinx 7 and SOURCE_DATE_EPOCH (pandas-dev#54653)

* DOC: fix build failure with sphinx 7 and SOURCE_DATE_EPOCH

* DOC: address review comments

Author: rebecca-palmer

doc/source/conf.py

@@ -162,7 +162,7 @@
 # General information about the project.
 project = "pandas"
 # We have our custom "pandas_footer.html" template, using copyright for the current year
-copyright = f"{datetime.now().year}"
+copyright = f"{datetime.now().year},"
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the