[pylint] Pylint 2.10 - unspecified-encoding

Pylint 2.10 added new default checks [1]:

unspecified-encoding:
  Emitted when open() is called without specifying an encoding [2]

[1] https://pylint.pycqa.org/en/latest/whatsnew/2.10.html
[2] https://github.com/PyCQA/pylint/issues/3826



Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>