Bump symfony/phpunit-bridge from 6.3.6 to 6.4.0 (#276)

Bumps [symfony/phpunit-bridge](https://github.com/symfony/phpunit-bridge) from 6.3.6 to 6.4.0.
- [Release notes](https://github.com/symfony/phpunit-bridge/releases)
- [Changelog](https://github.com/symfony/phpunit-bridge/blob/6.3/CHANGELOG.md)
- [Commits](symfony/phpunit-bridge@v6.3.6...v6.4.0)

---
updated-dependencies:
- dependency-name: symfony/phpunit-bridge
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

composer.json

@@ -20,7 +20,7 @@
     "require-dev": {
         "symfony/dotenv": "4.4.*",
         "squizlabs/php_codesniffer": "^3.2",
-        "symfony/phpunit-bridge": "6.3.*",
+        "symfony/phpunit-bridge": "6.4.*",
         "symfony/browser-kit": "4.4.*"
     },
     "config": {