composer.json: remove --prefer-lowest

[mfn]

Summary

IMHO it's impractical to expect this package to have to work with the
"first release of Laravel for any major release" even when there are
already sever more releases: no one is/should stick to that version.

This is a re-submit of #1076

See also for recent breakaes

• Check for traits recursively #1216 (comment)
• Generate helpers after package discovery #1185 (comment)

Note: PHP8 already didn't include it

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Misc. change (internal, infrastructure, maintenance, etc.)

Checklist

• Existing tests have been adapted and/or new tests have been added
• Add a CHANGELOG.md entry
• Update the README.md
• Code style has been fixed via composer fix-style

[mfn]

@barryvdh can you take a look at this issue? All PRs currently fail due to prefer-lowest not working and, TBH, I don't have much interest in chasing down the actual minimum version and would rather get the ball rolling forward (though happy if someone else has time to figure this out)

[Messhias]

I would like to do a review on this, but it's seems blocked to me.