[TRIVIAL] Set version to 2.4.0-b3 in develop

[ximinez]

High Level Overview of Change

This PR only changes the version number. It will be merged as
soon as Github CI actions successfully complete. (And it gets an approval.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.1%. Comparing base (3d02580) to head (1b75dc8).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #5261     +/-   ##
=========================================
- Coverage     78.1%   78.1%   -0.0%     
=========================================
  Files          790     790             
  Lines        67340   67340             
  Branches      8154    8155      +1     
=========================================
- Hits         52588   52585      -3     
- Misses       14752   14755      +3     

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

... and 5 files with indirect coverage changes