adding "/proc/sys/kernel/hostname" to paths in _parse_hostname_string

[CinisSec]

Adds the /proc/sys/kernel/hostname path to the paths mentioned in issue 606

[Miauwkeru]

Could you change the title of the PR and your commit message according to our commit style guidelines?

https://docs.dissect.tools/en/latest/contributing/style-guide.html#commit-message-style-and-formatting

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 77.70%. Comparing base (79aa5dd) to head (6e5428a). Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #704   +/-   ##
=======================================
  Coverage   77.70%   77.70%           
=======================================
  Files         326      326           
  Lines       28481    28481           
=======================================
  Hits        22131    22131           
  Misses       6350     6350           

Flag	Coverage Δ
unittests	77.70% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.