fix if clause in job skip logic (#3825)

Author: masci

.github/workflows/compliance.yml

@@ -14,7 +14,7 @@ env:
 
 jobs:
   check-license-compliance-cpu:
-    if: github.repository_owner == 'deepset-ai'
+    if: ${{ !github.event.pull_request.head.repo.fork }}
     name: Check CPU dependencies
     runs-on: ubuntu-latest
     steps:
@@ -58,7 +58,7 @@ jobs:
           channel: ${{ env.SLACK_ALERT_CHANNEL }}
 
   check-license-compliance-gpu:
-    if: github.repository_owner == 'deepset-ai'
+    if: ${{ !github.event.pull_request.head.repo.fork }}
     name: Check GPU dependencies
     runs-on: ubuntu-latest
     steps: