Skip running jobs on fork `develop` where they lack secrets (#22561)

* Skip running jobs on fork `develop` where they lack secrets

* Fix contexts

.github/workflows/build_develop.yml

@@ -9,6 +9,8 @@ on:
 jobs:
   build:
     name: "Build & Upload source maps to Sentry"
+    # Only respect triggers from our develop branch, ignore that of forks
+    if: github.repository == 'vector-im/element-web'
     runs-on: ubuntu-latest
     environment: develop
     steps: