allow using mpirun to run tests

[BenWibking]

Description

Please write a short paragraph describing what changes this pull request makes to the code. It should provide sufficient context so that a reviewer can efficiently browse the source code changes.

Related issues

Are there any GitHub issues that are fixed by this pull request? Add a link to them here.

Checklist

Before this pull request can be reviewed, all of these tasks should be completed. Denote completed tasks with an x inside the square brackets [ ] in the Markdown source below:

• [ ] I have added a description (see above).
• [ ] I have added a link to any related issues see (see above).
• [ ] I have read the Contributing Guide.
• [ ] I have added tests for any new physics that this PR adds to the code.
• [ ] I have tested this PR on my local computer and all tests pass.
• [ ] I have manually triggered the GPU tests with the magic comment /azp run.
• [ ] I have requested a reviewer for this PR.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[BenWibking]

With CMake 3.29 or newer, this can be accomplished by adding -DCMAKE_TEST_LAUNCHER=mpirun to the CMake command-line flags, so this PR is unnecessary.