Add tests directory to exclusion PHP Codesniffer pattern.

Author: Potherca

.config/phpcs.xml.dist

@@ -15,7 +15,7 @@
     <arg name="colors"/>
 
     <file>.</file>
-    <exclude-pattern>*(.config|vendor|persistent-storage)/*</exclude-pattern>
+    <exclude-pattern>*(.config|vendor|tests)/*</exclude-pattern>
 
     <rule ref="PHPCompatibility"/>
     <config name="testVersion" value="8.0-"/>