Merge pull request #2508 from signalwire/gha

[GHA] Pin workflow to repository.

.github/workflows/build.yml

@@ -15,7 +15,7 @@ concurrency:
 jobs:
   excludes:
     name: 'Excludes'
-    if: github.repository == 'signalwire/freeswitch'
+    if: github.event.pull_request.head.repo.full_name == github.repository
     runs-on: ubuntu-latest
     outputs:
       deb: ${{ steps.deb.outputs.excludes }}
@@ -49,7 +49,7 @@ jobs:
 
   deb:
     name: 'DEB'
-    if: github.repository == 'signalwire/freeswitch'
+    if: github.event.pull_request.head.repo.full_name == github.repository
     permissions:
       id-token: write
       contents: read