An attempt at working around kart message encoding issues

[hamishcampbell]

In some situations Kart is emitting messages that cannot be decoded as UTF-8.

File "C:\Users/xxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\koordinates\core\kart_task.py", line 106, in on_stdout
  self.on_stdout(ba)
  ^^^^^^^^^^^^^^
  File "C:\Users/xxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\koordinates\core\kart_task.py", line 106, in on_stdout
  self.on_stdout(ba)
  ^^^^^^^^^^^^^^
  File "C:\Users/xxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\koordinates\core\kart_task.py", line 106, in on_stdout
  self.on_stdout(ba)
  ^^^^^^^^^^^^^^
  [Previous line repeated 5 more times]
  File "C:\Users/xxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\koordinates\core\kart_task.py", line 185, in on_stdout
  val = ba.data().decode('UTF-8')
  ^^^^^^^^^^^^^^^^^^^^^^^^^
 UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe9 in position 117: invalid continuation byte
 
 The above exception was the direct cause of the following exception:
 
 SystemError: returned a result with an exception set
 
 The above exception was the direct cause of the following exception:
 
 SystemError: returned a result with an exception set
 
 The above exception was the direct cause of the following exception:
 
 Traceback (most recent call last):
  File "C:\Users/xxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\koordinates\core\kart_task.py", line 211, in run
  res = super().run()
  ^^^^^^^^^^^^^
  File "C:\Users/xxxxxxx/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\koordinates\core\kart_task.py", line 113, in run
  res = process.run(self._feedback)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 SystemError: returned a result with an exception set

We're yet to understand the exact source of the message and haven't been able to reproduce outside of a particular environment, however this change attempts to harden the decode of the CLI response.

[github-actions]

Plugin ready!

A test version of this PR is available for testing here.

(Built from commit e2c3ecb)

[hamishcampbell]

Superceded by #319