Fix detection of PRs from forks

Signed-off-by: Hidde Beydals <hello@hidde.co>

.github/workflows/bootstrap.yaml

@@ -9,7 +9,7 @@ on:
 jobs:
   github:
     runs-on: ubuntu-latest
-    if: ${{ github.repository_owner == 'fluxcd' }}
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
     steps:
       - name: Checkout
         uses: actions/checkout@v2

.github/workflows/scan.yaml

@@ -24,7 +24,7 @@ jobs:
   snyk:
     name: Snyk
     runs-on: ubuntu-latest
-    if: ${{ github.repository_owner == 'fluxcd' }}
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == github.repository
     steps:
       - uses: actions/checkout@v2
       - name: Run Snyk to check for vulnerabilities