bring back original Accept-Encoding

[jettify]

as discussed in #258 I am reverting encoding part

[codecov]

Codecov Report

Merging #433 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #433      +/-   ##
==========================================
+ Coverage   87.24%   87.26%   +0.02%     
==========================================
  Files           8        8              
  Lines         486      487       +1     
==========================================
+ Hits          424      425       +1     
  Misses         62       62

Impacted Files	Coverage Δ
aiobotocore/endpoint.py	90.74% <100%> (+0.05%)	⬆️

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