Reduce deprecation-noise in composer test output on PHP 8.5

[coenjacobs]

Summary

composer test currently passes, but output is heavily flooded by deprecation warnings from tooling dependencies on PHP 8.5 (Composer PHAR internals, PHPMD, and PDepend).

Why this matters

• Makes CI and local pre-release verification noisy.
• Reduces signal-to-noise ratio for real failures.
• Increases risk of missing important errors in long logs.

Evidence

During a full run (docker compose run --rm builder composer test), the suite completes successfully, but emits many deprecation notices from vendor tooling before/around successful checks.

Proposed fixes

• Update/pin dev tooling to versions compatible with current PHP runtime.
• If needed, split tooling steps by PHP version (run tools requiring older compatibility on a compatible runtime, keep product tests on the target runtime).
• Ensure CI output remains actionable by minimizing non-actionable deprecation noise.