Extend color range to pretty-display dye schemes

[trappitsch]

Extend color range in dark and light scheme, according to these definitions:

https://sciencenotes.org/visible-light-spectrum-wavelengths-and-colors/

[codecov]

Codecov Report

Attention: Patch coverage is 79.16667% with 5 lines in your changes missing coverage. Please review.

Project coverage is 94.03%. Comparing base (5c2fa68) to head (c005e12).
Report is 17 commits behind head on main.

Files	Patch %	Lines
src/rimsschemedrawer/utils.py	76.19%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #23      +/-   ##
==========================================
+ Coverage   94.02%   94.03%   +0.01%     
==========================================
  Files           9        9              
  Lines         669      671       +2     
==========================================
+ Hits          629      631       +2     
  Misses         40       40              

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