Remove RealtimeClock

[christophfroehlich]

RealtimeClock got deprecated on Jazzy and Rolling with their sync within the last days.

Fixes #241 and closes #23

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.66%. Comparing base (2fbe2ea) to head (ed0848b).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #261      +/-   ##
==========================================
+ Coverage   70.72%   71.66%   +0.94%     
==========================================
  Files           9        8       -1     
  Lines         526      487      -39     
  Branches       87       77      -10     
==========================================
- Hits          372      349      -23     
+ Misses         99       91       -8     
+ Partials       55       47       -8     

Flag	Coverage Δ
unittests	71.66% <ø> (+0.94%)	⬆️

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[saikishor]

As we already did a release deprecating it.
I think we should be fine as we discussed