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>

composer.json

@@ -42,7 +42,7 @@
     "php-http/psr7-integration-tests": "dev-master",
     "phpstan/phpstan": "^0.12",
     "phpunit/phpunit": "^8.5 || ^9.5",
-    "squizlabs/php_codesniffer": "^3.5",
+    "squizlabs/php_codesniffer": "^3.6",
     "weirdan/prophecy-shim": "^1.0 || ^2.0.2"
   },
   "provide": {