composer(deps): update sirbrillig/phpcs-variable-analysis requirement

Updates the requirements on [sirbrillig/phpcs-variable-analysis](https://github.com/sirbrillig/phpcs-variable-analysis) to permit the latest version.
- [Release notes](https://github.com/sirbrillig/phpcs-variable-analysis/releases)
- [Commits](sirbrillig/phpcs-variable-analysis@v2.11.20...v2.11.21)

---
updated-dependencies:
- dependency-name: sirbrillig/phpcs-variable-analysis
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

composer.json

@@ -34,7 +34,7 @@
     "php": "~8.1.0 || ~8.2.0 || ~8.3.0 || ~8.4.0 || ~8.5.0",
     "dealerdirect/phpcodesniffer-composer-installer": "^1.0.0",
     "friendsofphp/php-cs-fixer": "^3.65.0",
-    "sirbrillig/phpcs-variable-analysis": "^2.11.20",
+    "sirbrillig/phpcs-variable-analysis": "^2.11.21",
     "slevomat/coding-standard": "^8.15.0",
     "squizlabs/php_codesniffer": "^3.11.1"
   },