Bump codecov/codecov-action from 3 to 4 (#817)

* 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]>

* Update .github/workflows/UnitTests.yml

---------

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

Author: dependabot[bot]

.github/workflows/UnitTests.yml

@@ -71,8 +71,9 @@ jobs:
 
     - uses: julia-actions/julia-runtest@v1
     - uses: julia-actions/julia-processcoverage@v1
-    - uses: codecov/codecov-action@v3
+    - uses: codecov/codecov-action@v4
       with:
+        token: ${{ secrets.CODECOV_TOKEN }}
         files: lcov.info
     - uses: julia-actions/julia-uploadcoveralls@v1
       continue-on-error: true