style: ignore rule that doesn't apply on PHP < 7.4

Author: bpolaszek

phpcs.xml.dist

@@ -18,6 +18,7 @@
         <exclude name="Generic.Formatting.MultipleStatementAlignment"/>
         <exclude name="Squiz.Commenting.FunctionComment.SpacingAfterParamType"/>
         <exclude name="SlevomatCodingStandard.Functions.StaticClosure"/>
+        <exclude name="SlevomatCodingStandard.ControlStructures.RequireNullCoalesceEqualOperator.RequiredNullCoalesceEqualOperator"/>
     </rule>
 
     <file>src/</file>