Migrate from slevomat/coding-standard to shipmonk/coding-standard

This simplifies the phpcs configuration by using the ShipMonkCodingStandard
ruleset instead of manually specifying all rules.

Author: JanTvrdik

composer.json

@@ -23,7 +23,7 @@
         "shipmonk/composer-dependency-analyser": "^1.8.1",
         "shipmonk/dead-code-detector": "^0.9.0",
         "shipmonk/name-collision-detector": "^2.1.1",
-        "slevomat/coding-standard": "^8.16.0"
+        "shipmonk/coding-standard": "^0.2.0"
     },
     "suggest": {
         "phpunit/phpunit": "^9.6.22 for running tests that use RuleTestCase"