Actions: Disable merge-announce workflow on forks

Author: vidplace7

.github/workflows/merge-announce.yml

@@ -6,6 +6,8 @@ on:
 
 jobs:
   announcepush:
+    # Do not run this workflow in forks
+    if: ${{ github.repository == 'armbian/build' }}
     runs-on: ubuntu-latest
     steps:
       - name: Get repo