Cleanup baseline

Author: danog

psalm-baseline.xml

@@ -2888,11 +2888,6 @@
       <code><![CDATA[$expected_value_type]]></code>
     </ImplicitToStringCast>
   </file>
-  <file src="tests/Config/ConfigTest.php">
-    <InvalidArgument>
-      <code><![CDATA[$classloader]]></code>
-    </InvalidArgument>
-  </file>
   <file src="tests/Config/PluginListTest.php">
     <InvalidArgument>
       <code><![CDATA[$this->composer_lock]]></code>