mem: replace flate.Reader reference

[ash2k]

This interface has nothing to do with compression and there are no other references to that package in the codebase. If we remove the reference we same compiler and linker some work - no need to parse, compile, link that package just to use one interface from it (assuming no other references from the codebase).

RELEASE NOTES:

• mem: remove dependency on compress/flate package

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.88%. Comparing base (3ffb98b) to head (614fd7f).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7595      +/-   ##
==========================================
+ Coverage   81.87%   81.88%   +0.01%     
==========================================
  Files         361      361              
  Lines       27813    27813              
==========================================
+ Hits        22773    22776       +3     
- Misses       3843     3846       +3     
+ Partials     1197     1191       -6     

Files with missing lines	Coverage Δ
mem/buffer_slice.go	96.20% <ø> (ø)

... and 27 files with indirect coverage changes

[dfawley]

cc @PapaCharlie

[PapaCharlie]

Yep makes sense to me!