Move CI from Travis to GitHub actions

[oschulz]

No description provided.

[codecov]

Codecov Report

Merging #9 (5ac49f8) into master (cbd4141) will increase coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master       #9      +/-   ##
==========================================
+ Coverage   99.00%   99.10%   +0.09%     
==========================================
  Files           4        4              
  Lines         101      112      +11     
==========================================
+ Hits          100      111      +11     
  Misses          1        1              

Impacted Files	Coverage Δ
src/util.jl	100.00% <0.00%> (ø)
src/unsafe_array.jl	100.00% <0.00%> (ø)
src/uview.jl	97.67% <0.00%> (+0.30%)	⬆️

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