chore: Update psalm to v6.16.0

[kesselb]

Summary

Refined version of #11224

Psalm works on CI, but is broken locally with newer PHP versions.

Main different to the previous attempt: psalm/phar is moved to vendor-bin and merged with psalm-stubs. composer.json forces php to 8.1 (for nextcloud 32). For psalm itself that is not necessary (and covered by the php version in psalm.xml). Moving the vendor-bin allows to use the latest version.

Using vimeo/psalm (instead of the phar) failed with Fatal error: Cannot redeclare function Amp\delay() (previously declared in vendor/amphp/amp/lib/functions.php:131) in vendor-bin/psalm/vendor/amphp/amp/src/functions.php on line 64, hence we stick with phar for now.

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI

[kesselb]

Problem 1
    - psalm/phar is locked to version 6.16.1 and an update of this package was not requested.
    - psalm/phar 6.16.1 requires php ^8.2 -> your php version (8.1.34) does not satisfy that requirement.

I'd forgot 🙈