Update PR test coverage for vitest instead of jest

[ClaraUktar]

🧽 Maintenance Description

We need to update the job showing the test coverage for a PR to use vitest and corresponding coverage libraries, because we already have and will continue to replace jest with vitest in our codebase, and want to see test coverage for each PR.

✔️ Acceptance Criteria

• Test coverage is shown for each PR in all repos using vitest
• The coverage is also shown in case of failing tests

🔗 References and Tools

To show coverage for vitest, the following library could be used: https://github.com/davelosert/vitest-coverage-report-action

How to test changes:

1. Create a branch in this repository containing the changes made to the workflows
2. Create a branch in a repo where the tests should be executed, e.g. data-graph, which refers to the branch in this repo in its manage-pr workflow, e.g. uses: dot-base/.github/.github/workflows/manage-pr.yml@new-pr-coverage
3. Create a PR from the branch in step 2. The updated workflow should then be executed on GitHub.