Sync development

[gmazzap]

• Add support for custom env config files in 'vip-composer-plugin-env-config' packages, see #14
• Upgraded dev dependencies and fix newly found issues
• Modernize actions used in worfklows and run tests for PHP 8.3
• Remove license header from each file

Please check if the PR fulfills these requirements

• [x] The commit message follows our guidelines
• [ ] Tests for the changes have been added (for bug fixes/features)
• [x] Docs have been added/updated (for bug fixes/features)

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

docs update, deps update

What is the current behavior? (You can also link to an open issue here)

n/a

What is the new behavior (if this is a feature change)?

See #14

Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

no

Other information: