Remark/URL redirection check: update GitHub URL

[rodrigoprimo]

Description

This PR updates a GitHub URL in the CHANGELOG.md and README.md files. GitHub changed the URL and the old one started redirecting to a new address causing remark to fail the CI build with an "Unexpected redirecting URL" warning.

Example:

CHANGELOG.md
656:1-656:166 warning Unexpected redirecting URL `https://docs.github.com/en/actions/security-for-github-actions/using-artifact-attestations/using-artifact-attestations-to-establish-provenance-for-builds`, expected final URL `https://docs.github.com/en/actions/how-tos/security-for-github-actions/using-artifact-attestations/using-artifact-attestations-to-establish-provenance-for-builds` no-dead-urls remark-lint

(https://github.com/PHPCSStandards/PHP_CodeSniffer/actions/runs/15910535915/job/44876452363?pr=1151#step:7:11)

Suggested changelog entry

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
  • This change is only breaking for integrators, not for external standards or end-users.
• Documentation improvement

PR checklist

• I have checked there is no other PR open for the same change.
• I have read the Contribution Guidelines.
• I grant the project the right to include and distribute the code under the BSD-3-Clause license (and I have the right to grant these rights).
• I have added tests to cover my changes.
• I have verified that the code complies with the projects coding standards.
• [Required for new sniffs] I have added XML documentation for the sniff.

[jrfnl]

Thanks @rodrigoprimo ! Will merge this once the build has passed.