Fix various linting issues

[reedy]

Looks like it's just down to reduced test coverage, at least partly from the changes in #418. Nothing really exercising any of the Libbi code

 ---------- coverage: platform linux, python 3.9.18-final-0 -----------
Name                                          Stmts   Miss  Cover   Missing
---------------------------------------------------------------------------
custom_components/myenergi/__init__.py           63      7    89%   98-111, 116-117
custom_components/myenergi/binary_sensor.py      33      0   100%
custom_components/myenergi/config_flow.py        66      0   100%
custom_components/myenergi/const.py              17      0   100%
custom_components/myenergi/entity.py             58      0   100%
custom_components/myenergi/number.py            100      1    99%   26
custom_components/myenergi/select.py             95     10    89%   68, 147, 152, 159, 164-166, 170-171, 175
custom_components/myenergi/sensor.py            217     11    95%   494-648
---------------------------------------------------------------------------
TOTAL                                           649     29    96%

[CJNE]

Thanks!