Add Support for Quadratic Constraints

[codecov[bot]]

Codecov Report

Merging #78 (202f269) into main (d4b7c94) will increase coverage by 1.40%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #78      +/-   ##
==========================================
+ Coverage   74.88%   76.28%   +1.40%     
==========================================
  Files          11       11              
  Lines         625      662      +37     
==========================================
+ Hits          468      505      +37     
  Misses        157      157              

Impacted Files	Coverage Δ
src/model.rs	86.11% <100.00%> (+1.08%)	:arrow_up:

[mmghannam]

Thanks a lot for the contribution!