[MRG] Remove khmer from actions

[mr-eyes]

Resolves #1947

[codecov]

Codecov Report

Merging #1950 (1f9a77e) into latest (3fcf2db) will increase coverage by 8.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           latest    #1950      +/-   ##
==========================================
+ Coverage   82.94%   90.96%   +8.02%     
==========================================
  Files         125       94      -31     
  Lines       13759     9479    -4280     
  Branches     1877     1877              
==========================================
- Hits        11412     8623    -2789     
+ Misses       2075      584    -1491     
  Partials      272      272              

Flag	Coverage Δ
python	90.96% <ø> (ø)
rust	?

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Impacted Files	Coverage Δ
src/core/src/ffi/index/mod.rs
src/core/src/storage.rs
src/core/tests/storage.rs
src/core/tests/test.rs
src/core/src/sketch/hyperloglog/mod.rs
src/core/src/cmd.rs
src/core/src/lib.rs
src/core/src/sketch/minhash.rs
src/core/src/index/sbt/mhbt.rs
src/core/src/ffi/signature.rs
... and 21 more

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