Bump codecov/codecov-action from 3 to 4 (#253)

* Bump codecov/codecov-action from 3 to 4

Bumps [codecov/codecov-action](https://github.com/codecov/codecov-action) from 3 to 4.
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v3...v4)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

* Add CODECOV_TOKEN and fail_ci_if_error option

* Correct syntax for specifying CODECOV_TOKEN

---------

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Graeme Watt <[email protected]>

.github/workflows/tests.yml

@@ -121,10 +121,12 @@ jobs:
 
     - name: Report coverage with Codecov
       if: ${{ matrix.root-version }}
-      uses: codecov/codecov-action@v3
+      uses: codecov/codecov-action@v4
       with:
+        fail_ci_if_error: true
         files: ./coverage.xml
         flags: unittests-${{ matrix.python-version }}
+        token: ${{ secrets.CODECOV_TOKEN }}
 
     - name: Save notebooks
       if: ${{ always() && matrix.root-version }}