Bump codecov/codecov-action from 3 to 4 (#81)

* 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] <support@github.com>

* Update ci.yml

* Update ci.yml

* Update ci.yml

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Hendrik Ranocha <ranocha@users.noreply.github.com>

.github/workflows/ci.yml

@@ -68,12 +68,12 @@ jobs:
         env:
           PYTHON: ""
       - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
         with:
           file: ./lcov.info
           flags: unittests
           name: codecov-umbrella
-          fail_ci_if_error: false
+          fail_ci_if_error: true
           token: ${{ secrets.CODECOV_TOKEN }}
       # The standard setup of Coveralls is just annoying for parallel builds, see, e.g.,
       # https://github.com/trixi-framework/Trixi.jl/issues/691