update go version to 1.14 for github workflow

[kevwan]

No description provided.

[codecov]

Codecov Report

Merging #976 (5ec522d) into master (b9e268a) will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #976      +/-   ##
==========================================
+ Coverage   81.77%   81.80%   +0.03%     
==========================================
  Files         250      250              
  Lines       13172    13172              
==========================================
+ Hits        10771    10776       +5     
+ Misses       2033     2027       -6     
- Partials      368      369       +1     

Impacted Files	Coverage Δ
core/mr/mapreduce.go	100.00% <0.00%> (+1.19%)	⬆️
core/load/sheddingstat.go	67.74% <0.00%> (+9.67%)	⬆️

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