Handle GDAL parallel process closing on quit

[dakk]

[2021-06-09 13:43:00,748] mainwindow: Quitting...
Process Process-14:
Traceback (most recent call last):
  File "/usr/lib/python3.9/multiprocessing/managers.py", line 801, in _callmethod
    conn = self._tls.connection
AttributeError: 'ForkAwareLocal' object has no attribute 'connection'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.9/multiprocessing/process.py", line 315, in _bootstrap
    self.run()
  File "/usr/lib/python3.9/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib/python3.9/site-packages/gweatherrouting-0.1-py3.9.egg/gweatherrouting/ui/gtk/charts/gdalrasterchart.py", line 104, in worker
    return_dict['surface'] = self.bandToSurface(i)
  File "<string>", line 2, in __setitem__
  File "/usr/lib/python3.9/multiprocessing/managers.py", line 805, in _callmethod
    self._connect()
  File "/usr/lib/python3.9/multiprocessing/managers.py", line 792, in _connect
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "/usr/lib/python3.9/multiprocessing/connection.py", line 507, in Client
    c = SocketClient(address)
  File "/usr/lib/python3.9/multiprocessing/connection.py", line 635, in SocketClient
    s.connect(address)
ConnectionRefusedError: [Errno 111] Connection refused
dakk ~/Repositories/MyRepos/gweatherrouting