Fix syntax error in release workflow (radius-project#7200)

# Description

* Fix syntax error in release workflow (failed in 0.30 release)

## Type of change

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Fixes: radius-project#7106

Signed-off-by: willdavsmith <[email protected]>
Co-authored-by: vinayada1 <[email protected]>

.github/workflows/release.yaml

@@ -37,7 +37,8 @@ jobs:
   generate_release_note:
     name: Generate release note from template
     runs-on: ubuntu-latest
-    if: github.repository == 'radius-project/radius' && github.event_name == 'pull_request' && github.event.pull_request.head.ref == 'main'
+    # We should only create the release note if this is a pull request against main
+    if: github.repository == 'radius-project/radius' && github.event_name == 'pull_request' && github.base_ref == 'main'
     env:
       RELNOTE_FOUND: false
     steps: