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)

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

Author: dependabot[bot]

composer.json

@@ -66,7 +66,7 @@
         "phpunit/phpunit": "^8.5.13 || ^9.3.8",
         "slim/http": "^1.2",
         "slim/psr7": "^1.3",
-        "squizlabs/php_codesniffer": "^3.5",
+        "squizlabs/php_codesniffer": "^3.6",
         "weirdan/prophecy-shim": "^1.0 || ^2.0.2"
     },
     "autoload": {