ci: remove unsupport syntax

.github/workflows/flutter_ci.yaml

@@ -101,12 +101,7 @@ jobs:
         working-directory: frontend/app_flowy
         run: flutter analyze
 
-<<<<<<< Updated upstream
-      - if: "$RUNNER_OS" == "Linux"
-        name: Build Flutter unit test lib
-=======
       - name: Build Flutter unit test lib
->>>>>>> Stashed changes
         working-directory: frontend
         run: |
           cargo make build-test-lib