MRG: fix beta clippy errors

[ctb]

Fixes errors encountered in #3547. Note: includes #3547!

error: struct pattern is not needed for a unit variant
   --> src/core/src/errors.rs:167:48
    |
167 |             SourmashError::CannotUpsampleScaled { .. } => SourmashErrorCode::CannotUpsampleScaled,
    |                                                ^^^^^^^ help: remove the struct pattern
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unneeded_struct_pattern
    = note: `-D clippy::unneeded-struct-pattern` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::unneeded_struct_pattern)]`

error: struct pattern is not needed for a unit variant
   --> src/core/src/errors.rs:169:50
    |
169 |             SourmashError::NeedsAbundanceTracking { .. } => {
    |                                                  ^^^^^^^ help: remove the struct pattern
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unneeded_struct_pattern

error: struct pattern is not needed for a unit variant
   --> src/core/src/errors.rs:190:46
    |
190 |             SourmashError::HLLPrecisionBounds { .. } => SourmashErrorCode::HLLPrecisionBounds,
    |                                              ^^^^^^^ help: remove the struct pattern
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unneeded_struct_pattern

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 87.99%. Comparing base (4045737) to head (ac517ce).
Report is 1 commits behind head on latest.

Files with missing lines	Patch %	Lines
src/core/src/errors.rs	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           latest    #3548   +/-   ##
=======================================
  Coverage   87.99%   87.99%           
=======================================
  Files         136      136           
  Lines       22230    22230           
  Branches     2225     2225           
=======================================
  Hits        19561    19561           
  Misses       2356     2356           
  Partials      313      313           

Flag	Coverage Δ
hypothesis-py	25.43% <ø> (ø)
python	92.32% <ø> (ø)
rust	81.95% <0.00%> (ø)

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