Update squizlabs/php_codesniffer requirement from ^3.5 to ^3.6

Updates the requirements on [squizlabs/php_codesniffer](https://github.com/squizlabs/PHP_CodeSniffer) to permit the latest version.
- [Release notes](https://github.com/squizlabs/PHP_CodeSniffer/releases)
- [Commits](squizlabs/PHP_CodeSniffer@3.5.0...3.6.0)

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

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

Author: dependabot[bot]

composer.json

@@ -30,7 +30,7 @@
     "require-dev": {
         "phpunit/phpunit": "^9.5.10",
         "slim/psr7": "^1.3.0",
-        "squizlabs/php_codesniffer": "^3.5"
+        "squizlabs/php_codesniffer": "^3.6"
     },
     "scripts": {
         "test": "phpunit --configuration phpunit.xml.dist",