chore: update justinrainbow/json-schema requirement || ^6.0

Updates the requirements on [justinrainbow/json-schema](https://github.com/jsonrainbow/json-schema) to permit the latest version.
- [Release notes](https://github.com/jsonrainbow/json-schema/releases)
- [Changelog](https://github.com/jsonrainbow/json-schema/blob/master/CHANGELOG.md)
- [Commits](jsonrainbow/json-schema@5.0.0...6.0.0)

---
updated-dependencies:
- dependency-name: justinrainbow/json-schema
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

composer.json

@@ -14,7 +14,7 @@
     "minimum-stability": "stable",
     "require": {
         "php": "^7.4|^8.0",
-        "justinrainbow/json-schema": "^5.0",
+        "justinrainbow/json-schema": "^5.0 || ^6.0",
         "mtdowling/jmespath.php": "^2.3",
         "ext-json": "*"
     },