psalm: supress false positive with newer Symfony

See https://github.com/symfony/symfony/issues/45627

psalm.xml

@@ -12,4 +12,11 @@
             <directory name="vendor" />
         </ignoreFiles>
     </projectFiles>
+    <issueHandlers>
+        <UndefinedDocblockClass>
+            <errorLevel type="suppress">
+                <referencedClass name="UnitEnum" />
+            </errorLevel>
+        </UndefinedDocblockClass>
+    </issueHandlers>
 </psalm>