feat: Add python3.9 support

[Pringled]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 70.27027% with 11 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
model2vec/distill/tokenizer.py	56.00%	11 Missing ⚠️

Files with missing lines	Coverage Δ
model2vec/distill/distillation.py	98.13% <100.00%> (+0.01%)	⬆️
model2vec/distill/inference.py	95.16% <100.00%> (+0.07%)	⬆️
model2vec/distill/utils.py	100.00% <100.00%> (ø)
model2vec/hf_utils.py	62.22% <100.00%> (+0.42%)	⬆️
model2vec/model.py	96.66% <100.00%> (ø)
tests/test_distillation.py	92.85% <100.00%> (+0.10%)	⬆️
tests/test_utils.py	100.00% <100.00%> (ø)
model2vec/distill/tokenizer.py	72.72% <56.00%> (+1.54%)	⬆️

[stephantul]

Begrudging approve