chore: enable dependabot for cs-fixer, openapi-extractor and psalm

[kesselb]

Summary

Enable dependabot for cs-fixer, openapi-extractor and psalm.

Each vendor-bin directory is an independent composer project, and therefore we need a dependabot configuration.

I wondered why cs:fixer did not support PHP 8.2 already.

composer run cs:fix
> php-cs-fixer fix
PHP needs to be a minimum version of PHP 7.4.0 and maximum version of PHP 8.1.*.
Current PHP version: 8.2.9.
To ignore this requirement please set `PHP_CS_FIXER_IGNORE_ENV`.
If you use PHP version higher than supported, you may experience code modified in a wrong way.

TODO

• Merge
• Expect a couple of bumps next week

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[nickvergessen]

As per #39271 we can't apply the updates at this point easily.
So not sure it makes sense to add dependabot already

[skjnldsv]

To merge or not to merge @kesselb ?

[kesselb]

Merge please because the code style adjustments are done and therefore this should work now.

At worst, we are getting a few dependabot pull requests and figure that it does not work yet 🙈