Bump slevomat dependency to allow 8.8.0

Update requirements to allow the latest version of slevomat.
mainly because of this change 
slevomat/coding-standard@fbc18cf

Author: mjrider

composer.json

@@ -18,7 +18,7 @@
     "require": {
         "php": "^7.1 || ^8.0",
         "squizlabs/php_codesniffer": "^3.0.0",
-        "slevomat/coding-standard": "^6.0 || ^7.0 || ^8.0 <= 8.6.2"
+        "slevomat/coding-standard": "^6.0 || ^7.0 || ^8.0 <= 8.8.0"
     },
     "require-dev": {
         "phpunit/phpunit": "^8.5.12"