add workflow_dispatch event in themes-weekly-pull.yml

Co-authored-by: per1234 <accounts@perglass.com>

Author: francescospissu

.github/workflows/themes-weekly-pull.yml

@@ -4,6 +4,7 @@ on:
   schedule:
     # run every friday at 5AM
     - cron: '0 5 * * 5'
+  workflow_dispatch:
 
 jobs:
   pull-from-jsonbin: