[MRG] Clean up clippy lints from 1.52

[luizirber]

New Rust release, new clippy recommendations =]

Also updates CI for nix to use nix-portable and better caching to lower runtimes.

[codecov]

Codecov Report

Merging #1505 (03f60bd) into latest (d57127b) will decrease coverage by 0.06%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           latest    #1505      +/-   ##
==========================================
- Coverage   89.88%   89.81%   -0.07%     
==========================================
  Files         124      124              
  Lines       19889    19888       -1     
  Branches     1515     1515              
==========================================
- Hits        17877    17863      -14     
- Misses       1783     1796      +13     
  Partials      229      229              

Flag	Coverage Δ
python	94.93% <ø> (ø)
rust	66.84% <88.88%> (-0.37%)	⬇️

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Impacted Files	Coverage Δ
src/core/src/sketch/minhash.rs	90.51% <75.00%> (-0.81%)	⬇️
src/core/src/from.rs	100.00% <100.00%> (ø)
src/core/src/sketch/hyperloglog/mod.rs	81.76% <100.00%> (ø)
src/core/src/sketch/nodegraph.rs	83.87% <100.00%> (ø)
src/core/src/signature.rs	58.18% <0.00%> (-1.22%)	⬇️
src/core/src/index/sbt/mod.rs	66.15% <0.00%> (-0.93%)	⬇️

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