Use Order[Version] to simplify MillAlg.content

[fthomas]

With our Version data type and its Order instance we can simplify MillAlg.content because we can just check if a Mill version is >= 0.7 and < 0.9 for example without extracting the minor version number.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.77%. Comparing base (fbf5c4b) to head (c023138).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3540      +/-   ##
==========================================
- Coverage   89.81%   89.77%   -0.04%     
==========================================
  Files         171      171              
  Lines        4989     4970      -19     
  Branches      500      494       -6     
==========================================
- Hits         4481     4462      -19     
  Misses        508      508              

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