update changelog

[GertjanBisschop]

• Ran statistical tests for multimerger
• Modified date in changelog.

Also modified year of previous release.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (804e036) 98.70% compared to head (133ff44) 91.52%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2258      +/-   ##
==========================================
- Coverage   98.70%   91.52%   -7.19%     
==========================================
  Files          11       20       +9     
  Lines        4022    11337    +7315     
  Branches      907     2304    +1397     
==========================================
+ Hits         3970    10376    +6406     
- Misses         28      523     +495     
- Partials       24      438     +414     

Flag	Coverage Δ
C	91.52% <100.00%> (?)
python	98.70% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
lib/msprime.c	86.12% <100.00%> (ø)

... and 8 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7ee1619...133ff44. Read the comment docs.

[jeromekelleher]

LGTM, let's ship!