vote: move benchmarks to bencher 0.1.5

[puhtaytow]

Problem

Our benchmarking setup relies on nightly compiler which is not what we use for actual builds of agave. Using the same compiler (stable) for releases and benches would be preferable #5931

Summary of Changes

Moved benchmarks to bencher 0.1.5.

[alexpyattaev]

@alessandrod, do you agree that this is an appropriate way of getting rid of nightly benches?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.2%. Comparing base (6bc9fb1) to head (87c2470).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master    #6090     +/-   ##
=========================================
- Coverage    83.2%    83.2%   -0.1%     
=========================================
  Files         856      856             
  Lines      376426   376426             
=========================================
- Hits       313321   313272     -49     
- Misses      63105    63154     +49     

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[alexpyattaev]

LGTM based on discussion in https://discord.com/channels/428295358100013066/439194979856809985/1392071885902057502