[chirp_users] help running chirp-next on RPI

[Dan Smith]

> (chirp:2413): Gtk-CRITICAL **: 04:58:49.028: gtk_distribute_natural_allocation: assertion 'extra_space >= 0' failed
> ERROR: <function ChirpMain.open_file at 0x7190d588> raised unexpected exception
> Traceback (most recent call last):
>   File "/home/pi/.local/lib/python3.7/site-packages/chirp/wxui/common.py", line 448, in run_safe
>     return fn(*args, **kwargs)
>   File "/home/pi/.local/lib/python3.7/site-packages/chirp/wxui/main.py", line 386, in open_file
>     editorset = ChirpEditorSet(radio, filename, self._editors)
>   File "/home/pi/.local/lib/python3.7/site-packages/chirp/wxui/main.py", line 119, in __init__
>     edit = self.MEMEDIT_CLS(radio, self._editors)
>   File "/home/pi/.local/lib/python3.7/site-packages/chirp/wxui/memedit.py", line 465, in __init__
>     self.set_cell_attrs()
>   File "/home/pi/.local/lib/python3.7/site-packages/chirp/wxui/memedit.py", line 482, in set_cell_attrs
>     attr.SetFitMode(wx.grid.GridFitMode.Ellipsize())
> AttributeError: 'GridCellAttr' object has no attribute 'SetFitMode'

This is likely due to an insufficiently new wx library. Please file a bug!

--Dan