Bump sirbrillig/phpcs-variable-analysis from 2.11.19 to 2.11.21

Bumps [sirbrillig/phpcs-variable-analysis](https://github.com/sirbrillig/phpcs-variable-analysis) from 2.11.19 to 2.11.21.
- [Release notes](https://github.com/sirbrillig/phpcs-variable-analysis/releases)
- [Commits](sirbrillig/phpcs-variable-analysis@v2.11.19...v2.11.21)

---
updated-dependencies:
- dependency-name: sirbrillig/phpcs-variable-analysis
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>