Lock CodeSniffer to 3.5.4

#645 (comment)

Author: shmax

composer.json

@@ -25,7 +25,7 @@
     "psr/http-message": "^1.0",
     "react/promise": "2.*",
     "simpod/php-coveralls-mirror": "^3.0",
-    "squizlabs/php_codesniffer": "^3.5.2"
+    "squizlabs/php_codesniffer": "3.5.4"
   },
   "config": {
     "preferred-install": "dist",