tokenizers 0.20.x has a broken pyproject.toml (missing project.version),
which causes installation failures when building from source (sdist),
particularly on Windows with uv. Update the constraint from ~=0.20.3
to >=0.21,<1 to avoid the broken versions.
Add regression tests to ensure the constraint stays correct.
Co-Authored-By: João <joao@crewai.com>