fix: leak on res aborted on non-range requests

[ronag]

Currently a non-range request which is aborted will leak a file descriptor. This PR fixes that.

[codecov-io]

Codecov Report

Merging #246 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #246      +/-   ##
==========================================
+ Coverage   75.22%   75.31%   +0.08%     
==========================================
  Files          11       11              
  Lines         553      555       +2     
  Branches      126      126              
==========================================
+ Hits          416      418       +2     
  Misses         48       48              
  Partials       89       89

Impacted Files	Coverage Δ
lib/ecstatic.js	72.92% <100%> (+0.23%)	⬆️

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[jfhbrook]

Thanks!