Fixes phpunit-workflow

[sreichel]

Description (*)

Remove --strict validation from phpunit test.

Fixed Issues (if relevant)

https://github.com/OpenMage/magento-lts/actions/runs/3364517392/jobs/5578955941

Run composer validate --strict
./composer.json is valid, but with a few warnings
See https://getcomposer.org/doc/04-schema.md for details on the schema
# General warnings
- require.phpunit/phpunit : unbound version constraints (*) should be avoided
- require.n98/magerun : unbound version constraints (*) should be avoided
Error: Process completed with exit code 1.

Questions or comments

@Flyingmana can you change this?

https://github.com/OpenMage/Testfield/blob/4c0f103c40ed908262d4f782db5f6da0aa52b3ae/composer.json#L22-L23

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All automated tests passed successfully (all builds are green)
• Add yourself to contributors list