Change version management to flit-scm, update copyright years

[trappitsch]

• Use flit-scm for version management with github tags (setuptools-scm under the hood)
• Update copyright to 2020-2023 in docs and __init__.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (60d4505) 99.87% compared to head (92a08b6) 99.87%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #83   +/-   ##
=======================================
  Coverage   99.87%   99.87%           
=======================================
  Files          51       51           
  Lines        3226     3226           
=======================================
  Hits         3222     3222           
  Misses          4        4           

Flag	Coverage Δ
unittests	99.87% <100.00%> (ø)

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

Files Changed	Coverage Δ
rimseval/__init__.py	100.00% <100.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.