Bump phpstan/phpstan from 1.12.27 to 1.12.28 in /tools (#761)

---
updated-dependencies:
- dependency-name: phpstan/phpstan
  dependency-version: 1.12.28
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]