fix sorting bug pedigrees

[GertjanBisschop]

In some cases the edge table that gets produced when recording additional nodes will end up not being correctly sorted. The added test replicates this bug. Test should probably part of the C codebase, but have not been able to produce a smaller example with the same issue.

[codecov]

Codecov Report

Merging #2224 (a191cb2) into main (873c2cc) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2224   +/-   ##
=======================================
  Coverage   91.52%   91.52%           
=======================================
  Files          20       20           
  Lines       11333    11334    +1     
  Branches     2302     2302           
=======================================
+ Hits        10372    10373    +1     
  Misses        523      523           
  Partials      438      438           

Flag	Coverage Δ
C	91.52% <100.00%> (+<0.01%)	⬆️
python	98.70% <ø> (ø)

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Files	Coverage Δ
lib/msprime.c	86.12% <100.00%> (+<0.01%)	⬆️

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