databases/py-leveldb: Fix build with Python 3.12+
cc -fno-strict-overflow -Wsign-compare -Wunreachable-code -DNDEBUG -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -O2 -pipe -fstack-protector-strong -isystem /usr/local/include -fno-strict-aliasing -isystem /usr/local/include -fPIC -I/usr/local/include/python3.12 -c leveldb_object.cc -o build/temp.freebsd-15.0-RELEASE-p10-amd64-cpython-312/leveldb_object.o -I/usr/local/include -I. -fno-builtin-memcmp -O2 -fPIC -pthread -Wall -DOS_FREEBSD -DLEVELDB_PLATFORM_POSIX
leveldb_object.cc:795:19: error: use of undeclared identifier 'PyUnicode_AS_UNICODE'
795 | Py_UNICODE* c = PyUnicode_AS_UNICODE(p);
| ^1 error generated.
error: command '/usr/bin/cc' failed with exit code 1
ERROR Backend subprocess exited when trying to invoke build_wheel
- Error code 1