Ignore protobuf files in coverage (#2133)

Signed-off-by: Steve Coffman <steve@khanacademy.org>

.github/workflows/check-coverage

@@ -3,5 +3,8 @@
 set -euo pipefail
 GO111MODULE=off go get github.com/mattn/goveralls
 
-go test -covermode atomic -coverprofile=/tmp/coverage.out -coverpkg=./... $(go list github.com/99designs/gqlgen/... | grep -v _examples)
+go test -covermode atomic -coverprofile=/tmp/coverage.out.tmp -coverpkg=./... $(go list github.com/99designs/gqlgen/... | grep -v _examples)
+# ignore protobuf files
+cat /tmp/coverage.out.tmp | grep -v ".pb.go" > /tmp/coverage.out
+
 goveralls -coverprofile=/tmp/coverage.out -service=github -ignore='_examples/*/*,_examples/*/*/*,integration/*,integration/*/*,codegen/testserver/*/*,plugin/federation/testdata/*/*/*,*/generated.go,*/*/generated.go,*/*/*/generated.go,graphql/executable_schema_mock.go'