Update Deptrac URL to active repository (#1429)

The qossmic/deptrac repository was archived on 2026-02-17 and the
project moved to deptrac/deptrac, which is actively maintained
(v4.6.0 released 2026-02-02).

Deptrac was originally removed from the list in PR #1402 as part of
the "Remove 21 unmaintained/archived libraries" cleanup, but was
re-added with the stale URL in the subsequent "tidying up" commit
(bcbd70c). Point the entry at the active repository.

README.md

 *Libraries for performing static analysis of PHP code.*
 
 * [Dead Code Detector](https://github.com/shipmonk-rnd/dead-code-detector) - A PHPStan extension for finding unused PHP code.
-* [Deptrac](https://github.com/qossmic/deptrac) - A static analysis tool for enforcing dependency rules between architectural layers.
+* [Deptrac](https://github.com/deptrac/deptrac) - A static analysis tool for enforcing dependency rules between architectural layers.
 * [Exakat](https://github.com/exakat/exakat) - A static analysis engine for PHP.
 * [Larastan](https://github.com/larastan/larastan) - A PHPStan wrapper for Laravel that adds static analysis to Laravel projects.
 * [Mago](https://github.com/carthage-software/mago) - A toolchain for PHP that aims to improve the developer experience.