Fixes for 1.12 (#4655)

* fix missing locales
* bump composer packages
* changed translations
* assert timezone on customer
* include user accountNumber in excel export
* improve next customer number calculation
* fix z-index of contextmenu / action dropdown

translations/tasks.en.xlf

@@ -111,7 +111,7 @@
       </trans-unit>
       <trans-unit id="1ltxm9V" resname="task_todo">
         <source>task_todo</source>
-        <target>Task description</target>
+        <target>Task</target>
       </trans-unit>
     </body>
   </file>