Fix Theme Metadata Duplication and Add Missing Properties for Recent Pull Requests (#575)

* fix ability to add tags multiple times when rebuilding themes

* fix `createdAt` not being added for pull requests made prior

* adds tags property if it doesn't exist (old PRs)

* updated affected `theme.json` files

* updated more affected `theme.json` files

* fix action failing if new commits before finished

* make action only initiate when themes are changed

.github/workflows/update-theme-date.yml

@@ -1,13 +1,11 @@
 name: Update Theme Timestamps
 
 on:
-  pull_request:
-    branches:
-      - main
-    types: [closed]
   push:
     branches:
       - main
+    paths:
+      - 'themes/**'
 
 jobs:
   update-timestamp:
@@ -57,4 +55,5 @@ jobs:
             git add "themes/$theme/theme.json"
           done
           git commit -m "Update \`updated at\` field for \`$CHANGED_THEMES\`"
-          git push
+          git pull origin main --strategy-option=theirs
+          git push origin main