composer(deps-dev): bump phpunit/phpunit from 9.5.19 to 9.5.20

Bumps [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) from 9.5.19 to 9.5.20.
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/master/ChangeLog-9.5.md)
- [Commits](sebastianbergmann/phpunit@9.5.19...9.5.20)

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

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

composer.json

@@ -25,7 +25,7 @@
     "ergebnis/php-cs-fixer-config": "~4.4.0",
     "fakerphp/faker": "^1.19.0",
     "infection/infection": "~0.26.6",
-    "phpunit/phpunit": "^9.5.19",
+    "phpunit/phpunit": "^9.5.20",
     "psalm/plugin-phpunit": "~0.16.1",
     "vimeo/psalm": "^4.22.0"
   },