update build flow

Author: Eddie

.github/workflows/build.yaml

@@ -64,5 +64,5 @@ jobs:
           GITHUB_REF: ${{ github.ref }}
           GITHUB_RUN_ID: ${{ github.run_id }}
           GITHUB_REPOSITORY: ${{ github.repository }}
-          GITHUB_WORKFLOW: ${{ GITHUB_WORKFLOW }}
+          GITHUB_WORKFLOW: ${{ env.GITHUB_WORKFLOW }}
         run: python3 notify.py