Fix unable to have path object in argslist for localdriver

[jonathan-eq]

Issue
Resolves #9217

Approach
Call str on the object before joining it.

(Screenshot of new behavior in GUI if applicable)

• PR title captures the intent of the changes, and is fitting for release notes.
• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.
• Make sure unit tests pass locally after every commit (git rebase -i main --exec 'pytest tests/ert/unit_tests -n auto --hypothesis-profile=fast -m "not integration_test"')

When applicable

• When there are user facing changes: Updated documentation
• New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• Large PR: Prepare changes in small commits for more convenient review
• Bug fix: Add regression test for the bug
• Bug fix: Create Backport PR to latest release

[codspeed-hq]

CodSpeed Performance Report

Merging #9825 will not alter performance

_{Comparing jonathan-eq:fix-bugs7 (64e74df) with main (6a978df)}

Summary

✅ 24 untouched benchmarks

[xjules]

Is this the correct way how the inject parameters for the test? Or did you mean:

await driver.submit(42, "/usr/bin/env", "touch", Path(tmp_path), "testfile")

[jonathan-eq]

Path(tmp_path) and "testfile" should be combined