[TRIVIAL] Set version to 2.4.0-rc3

[legleux]

High Level Overview of Change

This PR only changes the version number. It will be merged as
soon as Github CI actions successfully complete.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.2%. Comparing base (cd7c628) to head (0a1ca06).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #5321   +/-   ##
=======================================
  Coverage     78.2%   78.2%           
=======================================
  Files          790     790           
  Lines        67740   67741    +1     
  Branches      8174    8178    +4     
=======================================
+ Hits         52961   52969    +8     
+ Misses       14779   14771    -8     
- Partials         0       1    +1     

Files with missing lines	Coverage Δ
src/libxrpl/protocol/BuildInfo.cpp	98.2% <ø> (ø)

... and 5 files with indirect coverage changes