fix json response parsing when not needed

[eguzki]

If the user does not want to parse response, let it be.

[codecov-commenter]

Codecov Report

Merging #25 into master will increase coverage by 0.19%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #25      +/-   ##
==========================================
+ Coverage   24.93%   25.12%   +0.19%     
==========================================
  Files          13       13              
  Lines         778      780       +2     
==========================================
+ Hits          194      196       +2     
  Misses        553      553              
  Partials       31       31              

Impacted Files	Coverage Δ
client/client.go	68.80% <100.00%> (+0.58%)	⬆️

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