Revert previous commit and update action with final state

`git diff --shortstat` will limit the output text avoiding spamming
the action output with large diffs (makes it a lot more difficult
to read) and the `--exit-code` option alone does what we want.

.github/workflows/test-build.yml

@@ -33,7 +33,7 @@ jobs:
         with:
           go-version: '1.16.2'
       - name: Run go tidy
-        run: make tidy && git diff --exit-code
+        run: make tidy && git diff --shortstat
       - name: Run go test
         run: make test
       - name: Run go build

go.mod

@@ -19,8 +19,5 @@ require (
 	k8s.io/apimachinery v0.21.3
 	k8s.io/client-go v0.21.3
 	k8s.io/klog/v2 v2.8.0
-)
-
-require (
 	sigs.k8s.io/controller-runtime v0.9.5
-)
+)