rust: update the rust-cpython crate to 0.7.0
This notably brings support for Python 3.10, and includes the panic message
when propagating a Rust panic as a Python exception.
https://github.com/dgrunwald/rust-cpython/blob/master/CHANGELOG.md#070---2021-10-09
Differential Revision: https://phab.mercurial-scm.org/D11630
from __future__ import absolute_import, print_function
import sys
for line in sys.stdin:
if line.lower() in ("message-id: \n", "in-reply-to: \n"):
line = line[:-2]
print(line, end="")