Prepare 0.40.0 release

[Mingun]

The last changes before the 0.40.0 release. Will be released in about 4-6 hours.

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 57.30%. Comparing base (a759d65) to head (a27709a).
⚠️ Report is 46 commits behind head on master.

Files with missing lines	Patch %	Lines
src/events/mod.rs	0.00%	1 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #962      +/-   ##
==========================================
+ Coverage   55.08%   57.30%   +2.21%     
==========================================
  Files          44       46       +2     
  Lines       16911    18192    +1281     
==========================================
+ Hits         9316    10425    +1109     
- Misses       7595     7767     +172     

Flag	Coverage Δ
unittests	57.30% <92.85%> (+2.21%)	⬆️

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