Drop observers from monty

[richfitz]

We are going to try a new approach in a follow-on PR

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.38%. Comparing base (3f721e2) to head (ac8bd65).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #76      +/-   ##
==========================================
- Coverage   99.43%   99.38%   -0.05%     
==========================================
  Files          64       64              
  Lines        4796     4752      -44     
==========================================
- Hits         4769     4723      -46     
- Misses         27       29       +2     

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[weshinsley]

OK - a bit of coverage to catch up on later

[richfitz]

yeah - the failure here is mostly because we reduced the denominator, but there are small holes to fill everywhere