[Backport generator] QMutexLocker is a template now, don't know how to handle this

(cherry picked from commit MeVisLab/pythonqt@2b6f1ce)

Author: usiems

generator/typesystem_core.xml

@@ -1317,7 +1317,8 @@
   <object-type name="QLibraryInfo"/>
   <object-type name="QMutex"/>
   <object-type name="QRecursiveMutex"/>
-  <value-type name="QMutexLocker">
+  <!-- QMutexLocker is a template in Qt6, we need to figure out what to do with it... -->
+  <value-type name="QMutexLocker" before-version="6">
     <!-- special handling for context handlers -->
     <inject-code class="pywrap-operators">PythonQt::Type_EnterExit</inject-code>
     <inject-code class="pywrap-h">