Change workflow to only check the diff against HEAD, rather than upda…

…te the index too

Signed-off-by: Hayden Blauzvern <hblauzvern@google.com>

.github/workflows/main.yml

@@ -44,5 +44,6 @@ jobs:
         run: go test -v -coverprofile=coverage.txt -covermode=atomic ./...
       - name: Upload Coverage Report
         uses: codecov/codecov-action@81cd2dc8148241f03f5839d295e000b8f761e378 # v3.0.0
+      # There must be no additional commits made by this workflow before this step
       - name: Ensure no files were modified as a result of the build
-        run: git update-index --refresh && git diff-index --quiet -I"^\/\/\s+protoc(-gen-go)?\s+v[0-9]+\.[0-9]+\.[0-9]+$" HEAD -- || git diff -I"^\/\/\s+protoc(-gen-go)?\s+v[0-9]+\.[0-9]+\.[0-9]+$" --exit-code
+        run: git diff -I"^\/\/\s+protoc(-gen-go)?\s+v[0-9]+\.[0-9]+\.[0-9]+$" --exit-code