Remove doctrine/dbal:^4 support

[mfn]

Summary

Remove doctrine/dbal:^4 support

Tests fail with:
PHP Fatal error: Declaration of Illuminate\Database\PDO\Concerns\ConnectsToDatabase::connect(array $params, $username = null, $password = null, array $driverOptions = []) must be compatible with Doctrine\DBAL\Driver::connect(array $params): Doctrine\DBAL\Driver\Connection in /home/runner/work/laravel-ide-helper/laravel-ide-helper/vendor/laravel/framework/src/Illuminate/Database/PDO/Concerns/ConnectsToDatabase.php on line 22

This was just recently added, before doctrine/dbal 4.0.0 was released, which happened 1 hour ago and tests don't work now.

Remove it until this is figured.

Marking it as internal change, because this wasn't release yet.

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]

Hmm, yeah, catch-22: either the unit tests fail or the integration tests :/

[mfn]

Finally figured it; feels a bit like a workaround though but it "only" affects Laravel 8 & 9, and with the pending Laravel 11 on the horizon and my plan to remove Laravel 8, IMHO this is a reasonable compromise.

As far as I understood the situation:
nesbot/carbon requires carbonphp/carbon-doctrine-types which requires doctrine/dbal

Due to the circumstances of how our integration tests work (I think), when installing laravel-ide-helper (without doctrine/dbal:^4 support), due to carbonphp/carbon-doctrine-types it tries to pick 4 and conflicts.

With adding the downgrading switch to composer, we fix the integration tests for now until we sort this out.

Also: at least until Laravel 10 it has an explicit conflicts rule in composer.json for dbal:^4 -> https://github.com/laravel/framework/blob/c4f46abce0e69737de35b71439943ac2a24d6ec3/composer.json#L123

@barryvdh I think this one is good to merge!

After that I will rebase and check #1503 and #1504