Update dev deps and CI workflows

[delatrie]

The PR contains the following changes:

• Enable Psalm 6 and psalm/plugin-phpunit 0.20 on newer PHP versions
• Bump Psalm to ^5.26.1 on older PHP versions
• Bump PHP code sniffer to ^4.0.1
• Fix errors reported by the latest Psalm version
• Remove --prefer-lowest from the CI test pipeline to ease the maintenance burden.
• Move static checks (composer validate, phpcs, and psalm`) to a separate job and always run them on a modern PHP
• Introduce concurrency to build workflow
• Make the test CI job titles shorter
• Display the Codecept version on the CI job summary pages
• Exclude autogenerated files from PHP code sniffer check
• Add explicit permissions to both workflows
• Add the missing type:docs label to labels-verify.yml