Add codecov for testing coverage

.github/workflows/build.yml

@@ -36,6 +36,13 @@ jobs:
         run: hatch run test
       - name: Verify that we can build the package
         run: hatch build
+      - name: Test coverage
+        run: pytest --cov --cov-report=xml
+        shell: bash -l {0}
+      - name: Upload coverage reports to Codecov
+        uses: codecov/codecov-action@v3
+        with:
+          use_oidc: true
 
   lint:
     name: Linting build
@@ -57,4 +64,5 @@ jobs:
         run: |
           python3 -m pip install --upgrade pip hatch
       - name: Check style against standards
-        run: hatch run lint
+        run: hatch run lint
+