Don't ever call Py_Finalize -- causes segfaults on exit

(cherry picked from commit 16c114b)
(cherry picked from commit ad9aa75)

Author: nyalldawson

src/python/qgspythonutilsimpl.cpp

@@ -266,7 +266,8 @@ bool QgsPythonUtilsImpl::startServerPlugin( QString packageName )
 void QgsPythonUtilsImpl::exitPython()
 {
   uninstallErrorHook();
-  Py_Finalize();
+  // causes segfault!
+  //Py_Finalize();
   mMainModule = nullptr;
   mMainDict = nullptr;
   mPythonEnabled = false;