Update psalm baseline for solved issue

Due to repairing the docblock on PersistentCollection::contains(),
this "known issue" is no longer an issue and should / must be
removed.

Author: tantegerda1

Diff for: psalm-baseline.xml

@@ -251,9 +251,6 @@
     </UnsupportedReferenceUsage>
   </file>
   <file src="src/Internal/Hydration/ObjectHydrator.php">
-    <InvalidArgument>
-      <code><![CDATA[$element]]></code>
-    </InvalidArgument>
     <PossiblyFalseArgument>
       <code><![CDATA[$index]]></code>
     </PossiblyFalseArgument>