Show help message when goimports/go mod tidy breaks the build

.github/workflows/pipeline.yml

@@ -39,6 +39,7 @@ jobs:
         run: |
           git status --porcelain
           if [ -n "$(git status --porcelain)" ]; then
+            echo 'To fix this check, run "goimports -w $(find . -name '*.go' | grep -v '_gen.go$') && go mod tidy"'
             exit 1
           fi