remove ll_representation argument

[GertjanBisschop]

Removed argument of DemographicEvent.get_ll_representation(). Solves #1037 as this is no longer used by stdpopsim.
The TestLowLevelRepresentation test suite is marked as containing tests that were only needed to ensure compatibility with stdpopsim. I couldn't see any calls containing the optional argument. Are there any other tests I can remove @jeromekelleher?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.23%. Comparing base (ac39f94) to head (f2c87dd).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2231   +/-   ##
=======================================
  Coverage   91.23%   91.23%           
=======================================
  Files          20       20           
  Lines       11828    11828           
  Branches     2295     2295           
=======================================
  Hits        10791    10791           
  Misses        568      568           
  Partials      469      469           

Flag	Coverage Δ
C	91.23% <100.00%> (ø)
python	98.68% <100.00%> (ø)

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[jeromekelleher]

I think it should be fine... I guess someone with an old stdpopsim who keeps their msprime up to date will hit problems?

Stdpopsim 0.2.0 came out over a year ago, but maybe the potential headaches aren't actually worth the small cleanup here.

https://github.com/popsim-consortium/stdpopsim/releases/tag/0.2.0

Let's keep this PR open and merge it in another year!

[jeromekelleher]

Merging this as stdpopsim 0.3.0 is now out, and it seems very unlikely that someone is using such an old stdpopsim without fully pinning to older versions of msprime also.

[jeromekelleher]

popsim-consortium/stdpopsim#535 was closed in 2021