exclude generated code from code coverage statistics

.codecov.yml is not working. We should filter out all
generated code that we don't want to be included in
the coverage report.

.circleci/config.yml

@@ -165,6 +165,8 @@ jobs:
           name: filter out DONTCOVER
           command: |
             excludelist="$(find ./ -type f -name '*.go' | xargs grep -l 'DONTCOVER')"
+            excludelist+=" $(find ./ -type f -name '*.pb.go')"
+            excludelist+=" $(find ./ -type f -path './tests/mocks/*.go')"
             for filename in ${excludelist}; do
               filename=$(echo $filename | sed 's/^./github.com\/cosmos\/cosmos-sdk/g')
               echo "Excluding ${filename} from coverage report..."