Update dependencies & drop support for node v4

[gucong3000]

Closes: #140

[codecov]

Codecov Report

Merging #141 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #141   +/-   ##
=======================================
  Coverage   99.82%   99.82%           
=======================================
  Files          13       13           
  Lines         568      568           
  Branches      116      116           
=======================================
  Hits          567      567           
  Partials        1        1

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