Add label exclusion support.

[chinthakagodawita]

This takes #16 and converts it to Typescript.

Closes #16.

[Codecov]

Codecov Report

Merging #86 (1a152b3) into master (3422469) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #86      +/-   ##
==========================================
+ Coverage   98.76%   98.83%   +0.07%     
==========================================
  Files           3        3              
  Lines         405      431      +26     
  Branches       80       64      -16     
==========================================
+ Hits          400      426      +26     
- Misses          0        5       +5     
+ Partials        5        0       -5     

Impacted Files	Coverage Δ
src/autoupdater.ts	98.40% <100.00%> (+0.08%)	⬆️
src/config-loader.ts	100.00% <100.00%> (ø)

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[chinthakagodawita]

Thanks @anarast !