Update squizlabs/php_codesniffer requirement from ^2.5 to ^3.9

Updates the requirements on [squizlabs/php_codesniffer](https://github.com/PHPCSStandards/PHP_CodeSniffer) to permit the latest version.
- [Release notes](https://github.com/PHPCSStandards/PHP_CodeSniffer/releases)
- [Changelog](https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/CHANGELOG.md)
- [Commits](PHPCSStandards/PHP_CodeSniffer@2.5.0...3.9.0)

---
updated-dependencies:
- dependency-name: squizlabs/php_codesniffer
  dependency-type: direct:development
...

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

composer.json

@@ -26,7 +26,7 @@
     "require-dev": {
         "ext-curl": "*",
         "phpunit/phpunit": "^9.5",
-        "squizlabs/php_codesniffer": "^2.5",
+        "squizlabs/php_codesniffer": "^3.9",
         "orchestra/testbench": "^4.18|^6.21|^8.0",
         "mockery/mockery": "^1.3"
     },