Update the link for the PHP_CodeSniffer repository

Documentation location/URL

* https://www.drupal.org/docs/contributed-modules/code-review-module/coder
* https://www.drupal.org/docs/contributed-modules/code-review-module/insta...
* https://www.drupal.org/docs/contributed-modules/code-review-module/php-c...

Problem/Motivation

In various places on the above listed pages, there are links to the PHP_CodeSniffer project which are outdated. There may be more outdated links, but these were the ones I noticed in particular.

The original project was abandoned in December 2023 and the project continues in a new location.

Old GitHub URL: https://github.com/squizlabs/PHP_CodeSniffer
New GitHub URL: https://github.com/PHPCSStandards/PHP_CodeSniffer

As the project wasn't moved, but continued in a blessed fork, GitHub does not redirect people, so the URLs in the documentation need updating.

Also see:
* https://www.drupal.org/project/coder/issues/3405657
* https://github.com/squizlabs/PHP_CodeSniffer/issues/3932

Proposed resolution

Please fix the links. I tried to do it myself, but don't have "edit" permission.

Remaining tasks