[ci] add fix for missing secrets in 3rd party forks

.github/workflows/rector_ci.yaml

@@ -28,11 +28,20 @@ jobs:
 
         runs-on: ubuntu-latest
         steps:
-            -   uses: actions/checkout@v2
+            # workaround for missing secret in fork PRs - see https://github.com/actions/checkout/issues/298
+            # see https://github.com/rectorphp/rector/commit/d395e1c28b8e6a56711dcc2e10490a82965850e4
+            -
+                if: github.event.pull_request.head.repo.full_name == github.repository
+                uses: actions/checkout@v2
                 with:
                     # Must be used to trigger workflow after push
                     token: ${{ secrets.ACCESS_TOKEN }}
 
+            # in forks, the token is not available - so we cannot us eit
+            -
+                if: github.event.pull_request.head.repo.full_name != github.repository
+                uses: actions/checkout@v2
+
             -
                 uses: shivammathur/setup-php@v1
                 with: