Logging: explicitly set encoding for file handler

[jenshnielsen]

This prevents issues where the broken pipe character (used for delimiting messages) cannot be written to the log file if the file has a different encoding. Reading the documentation it is not clear to which extend this may also be an issue for the stream handler used for the console logging. This writes to stderr. According to https://docs.python.org/3/library/sys.html#sys.stderr the encoding of stderr should be defined by local on oses other than windows so this probably works without issues on windows (but there are some limitations as noted in the stderr documentation) On most other platforms I would expect local encoding to be utf8 anyway.

[codecov]

Codecov Report

Merging #3327 (f3313f6) into master (ed825e6) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #3327   +/-   ##
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  Coverage   66.20%   66.20%           
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  Files         220      220           
  Lines       29250    29250           
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  Hits        19365    19365           
  Misses       9885     9885           

[FarBo]

This seems the way to go to fix the broken pipe encoding.
In a quick search, older Linux server encoding is something else. Newer versions are adapted to utf-8. The rest should be utf-8.

[jenshnielsen]

Looks like this fixed the reported issue. @astafan8 could you review