ci: fix update abi workflow (#259)

* ci: fix update abi workflow

* chore: use single quotes

Author: dsanders11

.github/workflows/update-abi.yml

@@ -64,7 +64,7 @@ jobs:
       if: ${{ steps.commit-changes.outputs.sha }}
       shell: bash
       env:
-        GITHUB_TOKEN: ${{ fromJSON(steps.secret-service.outputs.secrets).PR_APPROVER_GH_TOKEN }}
+        GITHUB_TOKEN: ${{ fromJSON(steps.secret-service.outputs.secrets || '{}').PR_APPROVER_GH_TOKEN }}
       run: |
         set -eo pipefail
         gh pr review "feat/update-abi-registry-${{ matrix.branch }}-${{ hashFiles('abi_registry.json') }}" --approve