Update dependency slevomat/coding-standard to v8

Author: renovate[bot]

build-cs/composer.json

@@ -2,7 +2,7 @@
 	"require-dev": {
 		"consistence-community/coding-standard": "^3.10",
 		"dealerdirect/phpcodesniffer-composer-installer": "^0.7.0",
-		"slevomat/coding-standard": "^7.0"
+		"slevomat/coding-standard": "^8.0"
 	},
 	"config": {
 		"allow-plugins": {