Channel resource leak fix

[rajmaniar]

No description provided.

[codecov-io]

Codecov Report

Merging #12 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #12      +/-   ##
==========================================
+ Coverage   94.89%   94.89%   +<.01%     
==========================================
  Files          55       55              
  Lines        2624     2625       +1     
==========================================
+ Hits         2490     2491       +1     
  Misses        134      134

Impacted Files	Coverage Δ
lib/src/client/impl/channel_impl.dart	96.85% <100%> (ø)	⬆️
lib/src/client/impl/client_impl.dart	94.39% <100%> (+0.05%)	⬆️

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