Update symfony/validator requirement from ^3.0||^4.0 to ^3.0||^4.0||^5.0 (#1400)

Updates the requirements on [symfony/validator](https://github.com/symfony/validator) to permit the latest version.
- [Release notes](https://github.com/symfony/validator/releases)
- [Changelog](https://github.com/symfony/validator/blob/6.2/CHANGELOG.md)
- [Commits](https://github.com/symfony/validator/commits/v5.4.19)

---
updated-dependencies:
- dependency-name: symfony/validator
  dependency-type: direct:development
...

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

composer.json

@@ -33,7 +33,7 @@
         "psr/http-message": "^1.0",
         "respect/coding-standard": "^3.0",
         "squizlabs/php_codesniffer": "^3.7",
-        "symfony/validator": "^3.0||^4.0"
+        "symfony/validator": "^3.0||^4.0||^5.0"
     },
     "suggest": {
         "ext-bcmath": "Arbitrary Precision Mathematics",