python-gmpy2: bump to 2.3.0

python-gmpy2: bump to 2.3.0

Changelog since 2.2.2:
- Add mpz.array() method for NumPy interaction
- Implement mpq.limit_denominator() functionality
- Add is_integer() method for mpz/mpq types
- Add mixed-mode arithmetic support for mpc types
- Enhanced formatting using context's rounding mode defaults
- Full free-threaded Python build support
- Fix memory leaks in MPFR/MPC cache and context exit
- Drop CPython 3.8 support (requires 3.9+)

Add test.sh.

gmpy2 2.3.0 switched to pyproject.toml with setuptools-scm for version
management. Add python-setuptools-scm/host to PKG_BUILD_DEPENDS.

Full changelog:
https://github.com/aleaxit/gmpy/releases

Signed-off-by: Alexandru Ardelean <redacted>