Generate __version__ at build to avoid slow importlib.metadata import

[hugovk]

Like hugovk/tinytext#195.

With Python 3.13.0rc1:

python -X importtime -c "import em_keyboard" 2> import.log && tuna import.log

Cuts 7 ms by removing the importlib.metadata import.

main

PR

hyperfine

❯ hyperfine --warmup 32 \
--prepare "git checkout rm-importlib.metadata" 'python3 -c "import em_keyboard"' \
--prepare "git checkout main"                  'python3 -c "import    em_keyboard"'
Benchmark 1: python3 -c "import em_keyboard"
  Time (mean ± σ):      37.4 ms ±   1.0 ms    [User: 30.2 ms, System: 6.3 ms]
  Range (min … max):    36.1 ms …  42.8 ms    64 runs

  Warning: Statistical outliers were detected. Consider re-running this benchmark on a quiet system without any interferences from other programs.

Benchmark 2: python3 -c "import    em_keyboard"
  Time (mean ± σ):      47.2 ms ±   8.4 ms    [User: 37.7 ms, System: 7.7 ms]
  Range (min … max):    44.8 ms … 105.0 ms    52 runs

  Warning: Statistical outliers were detected. Consider re-running this benchmark on a quiet system without any interferences from other programs.

Summary
  python3 -c "import em_keyboard" ran
    1.26 ± 0.23 times faster than python3 -c "import    em_keyboard"

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.96%. Comparing base (c2b1faf) to head (8ccef3c).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #142      +/-   ##
==========================================
- Coverage   98.49%   93.96%   -4.53%     
==========================================
  Files           2        2              
  Lines         199      199              
==========================================
- Hits          196      187       -9     
- Misses          3       12       +9     

Flag	Coverage Δ
macos-latest	91.95% <100.00%> (-2.52%)	⬇️
ubuntu-latest	93.96% <100.00%> (ø)
windows-latest	?

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