www/py-adblock: Fix build with py-maturin 0.14.0+
> Building for py39-adblock-0.5.0_44
💥 maturin failed
Caused by: The following metadata fields in `package.metadata.maturin` section of Cargo.toml are removed since maturin 0.14.0: classifier, requires-python, please set them in pyproject.toml as PEP 621 specifies.
- Error code 1
Stop.
make: stopped in /usr/ports/www/py-adblock
Approved by: portmgr (blanket)
Obtained from: https://github.com/ArniDagur/python-adblock/commit/7597cd0b841a0ede22ff4cec6b4b91fb7d26a805