Update symfony/var-dumper requirement from ^4.2 to ^4.2 || ^5.0

Updates the requirements on [symfony/var-dumper](https://github.com/symfony/var-dumper) to permit the latest version.
- [Release notes](https://github.com/symfony/var-dumper/releases)
- [Changelog](https://github.com/symfony/var-dumper/blob/master/CHANGELOG.md)
- [Commits](symfony/var-dumper@v4.2.0...v5.1.2)

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

composer.json

@@ -21,7 +21,7 @@
         "phpstan/phpstan": "^0.11.5",
         "phpunit/phpunit": "^8.0",
         "squizlabs/php_codesniffer": "^3.4",
-        "symfony/var-dumper": "^4.2"
+        "symfony/var-dumper": "^4.2 || ^5.0"
     },
     "autoload": {
         "psr-4": {