fix some clippy warnings

[jimexist]

Which issue does this PR close?

Closes #.

Rationale for this change

What changes are included in this PR?

Are there any user-facing changes?

[jimexist]

reduce enum size

[codecov-commenter]

Codecov Report

Merging #896 (750203f) into master (06f730e) will increase coverage by 0.00%.
The diff coverage is 84.21%.

@@           Coverage Diff           @@
##           master     #896   +/-   ##
=======================================
  Coverage   82.30%   82.30%           
=======================================
  Files         168      168           
  Lines       48031    48026    -5     
=======================================
- Hits        39533    39529    -4     
+ Misses       8498     8497    -1     

Impacted Files	Coverage Δ
arrow/src/error.rs	13.33% <0.00%> (ø)
parquet/src/data_type.rs	76.84% <ø> (-0.11%)	⬇️
parquet/src/schema/parser.rs	85.11% <0.00%> (-0.21%)	⬇️
parquet/src/util/bit_packing.rs	99.96% <ø> (ø)
parquet/src/util/bit_util.rs	93.19% <ø> (ø)
parquet_derive/src/lib.rs	0.00% <0.00%> (ø)
arrow/src/compute/kernels/comparison.rs	92.63% <100.00%> (ø)
arrow/src/util/test_util.rs	90.90% <100.00%> (ø)
parquet/src/record/reader.rs	90.46% <100.00%> (ø)
parquet/src/util/hash_util.rs	95.65% <100.00%> (-0.13%)	⬇️
... and 4 more

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[alamb]

Merged to master