add code coverage github action (#134)

.github/workflows/pr.yml

@@ -1,6 +1,7 @@
 name: PR sanity check
 
-on: pull_request
+on:
+  - push
 
 jobs:
   prcheck:
@@ -20,4 +21,6 @@ jobs:
       with:
         version: latest
     - name: Run tests
-      run: go test -v .
+      run: go test -race -covermode=atomic -coverprofile=coverage.out -v .
+    - name: Upload coverage reports to Codecov
+      uses: codecov/codecov-action@v3