fix: store selected language in session_local for al_change_language event

Author: jpagh

docassemble/AssemblyLine/data/questions/al_language.yml

@@ -41,5 +41,5 @@ code: |
 event: al_change_language
 code: |
   if "lang" in action_arguments():
-    al_user_language = action_argument("lang")
+    session_local.al_user_language = action_argument("lang")
     set_language(al_user_language)