chore(tests): Update psalm baseline

Signed-off-by: GitHub <noreply@github.com>

Author: nextcloud-command

build/psalm-baseline.xml

@@ -2216,11 +2216,6 @@
       <code>null</code>
     </NullArgument>
   </file>
-  <file src="lib/private/Files/ObjectStore/StorageObjectStore.php">
-    <InvalidReturnType>
-      <code>string</code>
-    </InvalidReturnType>
-  </file>
   <file src="lib/private/Files/Storage/Common.php">
     <ImplementedReturnTypeMismatch>
       <code>string|false</code>