snap: Add read access for ~/.gitconfig.local and ~/.config/git/* too

in hugo:gitconfig plug (personal-files interface) in case end users need
the flexibility of using additional custom git config files.

Fixes #10337

snap/snapcraft.yaml

@@ -28,7 +28,8 @@ plugs:
     interface: personal-files
     read:
       - $HOME/.gitconfig
-      - $HOME/.config/git/config
+      - $HOME/.config/git       # Allows $HOME/.config/git/config and more
+      - $HOME/.gitconfig.local  # See #10337
 
 environment:
   HOME: $SNAP_REAL_HOME