Reduce work in unicode_from_str()

Cargo.lock

Cargo.toml

bench/benchmark_dumps.py

bench/benchmark_loads.py

pydataclass

pynonstr

pynumpy

pysort

src/unicode.rs

test/test_datetime.py

test/test_memory.py

test/test_non_str_keys.py

test/test_numpy.py

test/test_type.py