[TRIVIAL] Set version to 2.4.0-rc4

[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 78.1%. Comparing base (53ea31c) to head (5bf3a30).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #5328   +/-   ##
=======================================
  Coverage     78.1%   78.1%           
=======================================
  Files          790     790           
  Lines        67908   67910    +2     
  Branches      8229    8229           
=======================================
+ Hits         53024   53032    +8     
+ Misses       14884   14878    -6     

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

... and 4 files with indirect coverage changes