Migrate to CodeCov v4 (#60)

# Migrate to CodeCov v4

## ♻️ Current situation & Problem
This PR migrates to the latest CodeCov action.

Note that v4 includes breaking changes. Every upload requires a token
now. However, current upload is broken anyways.


## ⚙️ Release Notes 
* Upgrade codecov action.


### Code of Conduct & Contributing Guidelines 

By submitting creating this pull request, you agree to follow our [Code
of
Conduct](https://github.com/StanfordBDHG/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordBDHG/.github/blob/main/CONTRIBUTING.md):
- [x] I agree to follow the [Code of
Conduct](https://github.com/StanfordBDHG/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordBDHG/.github/blob/main/CONTRIBUTING.md).

.github/workflows/create-and-upload-coverage-report.yml

@@ -44,7 +44,7 @@ jobs:
           xcrun xcresulttool merge ${{ inputs.coveragereports }} --output-path CodeCoverage.xcresult
           rm -rf ${{ inputs.coveragereports }}
     - name: Upload coverage to Codecov
-      uses: codecov/codecov-action@v3.1.1
+      uses: codecov/codecov-action@v4
       with:
         fail_ci_if_error: true
         token: ${{ secrets.token }}

.github/workflows/npm-test-and-coverage.yml

@@ -34,4 +34,4 @@ jobs:
       - name: Run the tests
         run: npm test
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4