Update phpstan/phpstan requirement from ^1.10.46 to ^1.10.50

Updates the requirements on [phpstan/phpstan](https://github.com/phpstan/phpstan) to permit the latest version.
- [Release notes](https://github.com/phpstan/phpstan/releases)
- [Changelog](https://github.com/phpstan/phpstan/blob/1.11.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@1.10.46...1.10.50)

---
updated-dependencies:
- dependency-name: phpstan/phpstan
  dependency-type: direct:development
...

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

composer.json

@@ -27,7 +27,7 @@
     "require-dev": {
         "phpunit/phpunit": "^9.6",
         "phpspec/prophecy-phpunit": "^2.0",
-        "phpstan/phpstan": "^1.10.46",
+        "phpstan/phpstan": "^1.10.50",
         "psr/http-factory": "^1.0",
         "squizlabs/php_codesniffer": "^3.8"
     },