disable running snyk if triggering user doesn't have access to the secret

.github/workflows/snyk-scan.yml

@@ -17,7 +17,7 @@ jobs:
   # https://github.com/snyk/actions/tree/master/php
   snyk-php:
     runs-on: ubuntu-latest
-    if: ${{ github.repository == 'PrivateBin/PrivateBin' }}
+    if: ${{ github.repository == 'PrivateBin/PrivateBin' && (github.event.pull_request.author_association == 'COLLABORATOR' || github.event.pull_request.author_association == 'OWNER') }}
     steps:
       - uses: actions/checkout@v5
       - name: Install Google Cloud Storage