doc: drop style year cache hint

The year for style updates was appended to the style sheet to prevent
any caching issues for clients browsing documentation. However, newer
versions of Sphinx will generate a hash value for us. Dropping the year
value and let Sphinx manage this responsibility.

Signed-off-by: James Knight <[email protected]>

Author: jdknight

doc/_themes/sphinx13b/theme.conf

@@ -1,4 +1,4 @@
 [theme]
 inherit = basic
-stylesheet = sphinx13b.css?20220220
+stylesheet = sphinx13b.css
 pygments_style = trac