Move CI from travis to github actions

[guimarqu]

Fix #418

[codecov]

Codecov Report

Merging #435 (8903e75) into master (3ff9f41) will increase coverage by 0.14%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #435      +/-   ##
==========================================
+ Coverage   80.12%   80.26%   +0.14%     
==========================================
  Files          52       52              
  Lines        4206     4196      -10     
==========================================
- Hits         3370     3368       -2     
+ Misses        836      828       -8     

Impacted Files	Coverage Δ
src/Algorithm/branching/branchingalgo.jl	90.75% <ø> (-1.44%)	⬇️
src/Algorithm/treesearch.jl	91.33% <100.00%> (+3.13%)	⬆️
src/Algorithm/branching/branchinggroup.jl	86.51% <0.00%> (-2.25%)	⬇️
src/decomposition.jl	98.47% <0.00%> (+0.49%)	⬆️
src/Algorithm/colgen.jl	96.63% <0.00%> (+0.74%)	⬆️
src/MOIcallbacks.jl	93.47% <0.00%> (+1.98%)	⬆️
src/ColunaBase/nestedenum.jl	97.56% <0.00%> (+2.32%)	⬆️

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