chore: hard code branch name in release-please.yml (#90)

Author: shubha-rajan

.github/workflows/release-please.yml

@@ -16,7 +16,7 @@ name: release-please
 on:
  push:
    branches:
-     - $default-branch
+     - main
 jobs:
  release-please:
    runs-on: ubuntu-latest