Update PyO3 version, rewrite row encoder

[scaramallion]

• Bump version to 2.1
• Update to PyO3 v0.24 and Rust v2024
• Rewrite the row encoder to be simpler and ~20% faster
• Drop support for Python 3.8, add it for Python 3.13
• Require numpy > v2

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (ca6fb46) to head (7128ef5).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #39   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines          112       112           
=========================================
  Hits           112       112           

Files with missing lines	Coverage Δ
rle/utils.py	100.00% <100.00%> (ø)

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