ci: Fix pre-commit diff check command

[rm3l]

Description of the change

Addendum to #148

Existing or Associated Issue(s)

Additional Information

Checklist

• Chart version bumped in Chart.yaml according to semver.
• Variables are documented in the values.yaml and added to the README.md. The pre-commit utility can be used to generate the necessary content. Use pre-commit run -a to apply changes.
• JSON Schema template updated and re-generated the raw schema via pre-commit hook.
• List tests pass for Chart using the Chart Testing tool and the ct lint command.

[sonarqubecloud]

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 SonarQube Cloud

[github-actions]

⚠️ Files changed after running the pre-commit hooks

Those changes should have been pushed automatically to your PR branch.

NOTE: If the PR checks are stuck after this additional commit, manually close the PR and immediately reopen it to trigger the checks again.