Switch from Criterion to Divan for benchmarks

[benbrandt]

Allows for tracking of allocations, not just timing. Since some of the tokenizer implementations can be very costly in terms of allocations, this will make it easier to check the performance improvements if tokenization runs are able to be skipped, both in terms of time, and memory allocation.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.34%. Comparing base (999d567) to head (1e1bc45).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #113      +/-   ##
==========================================
+ Coverage   98.96%   99.34%   +0.37%     
==========================================
  Files           6        6              
  Lines        1452     1374      -78     
==========================================
- Hits         1437     1365      -72     
+ Misses         15        9       -6     

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