[TASK] Update workflow refs from t3docs-ci-deploy to .github

Move reusable workflow reference to the org community health repo
(TYPO3-Documentation/.github) which is automatically accessible
to all org repos without allow-list changes.

Also fix input name: label-pattern -> label_pattern (underscore)
to match the reusable workflow's input definition.

Author: CybotTM

.github/workflows/backport.yml

@@ -6,6 +6,6 @@ on:
 
 jobs:
   backport:
-    uses: TYPO3-Documentation/t3docs-ci-deploy/.github/workflows/reusable-backport.yml@main
+    uses: TYPO3-Documentation/.github/.github/workflows/reusable-backport.yml@main
     with:
-      label-pattern: "backport *"
+      label_pattern: "backport *"