Saving issue in athena project in xasgui.py

[Ameyanagi]

@newville

There was _larch argument in left in the xasgui.py that causes issue in saving in the athena prj.

Traceback (most recent call last):
  File "/Users/ryuichi/mambaforge_x86_64/envs/xraylarch/lib/python3.11/site-packages/larch/wxxas/xasgui.py", line 706, in onExportAthenaProject
    self.save_athena_project(prjfile, groups)
  File "/Users/ryuichi/mambaforge_x86_64/envs/xraylarch/lib/python3.11/site-packages/larch/wxxas/xasgui.py", line 755, in save_athena_project
    aprj = AthenaProject(filename=filename, _larch=self.larch)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: AthenaProject.__init__() got an unexpected keyword argument '_larch'