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

rust/Cargo.lock

@@ -159,9 +159,9 b' dependencies = ['
 
 [[package]]
 name = "cpython"
-version = "0.6.0"
+version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8094679a4e9bfc8035572162624bc800eda35b5f9eff2537b9cd9aacc3d9782e"
+checksum = "b7d46ba8ace7f3a1d204ac5060a706d0a68de6b42eafb6a586cc08bebcffe664"
 dependencies = [
  "libc",
  "num-traits",
@@ -655,9 +655,9 b' dependencies = ['
 
 [[package]]
 name = "python27-sys"
-version = "0.6.0"
+version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5826ddbc5366eb0b0492040fdc25bf50bb49092c192bd45e80fb7a24dc6832ab"
+checksum = "94670354e264300dde81a5864cbb6bfc9d56ac3dcf3a278c32cb52f816f4dfd1"
 dependencies = [
  "libc",
  "regex",
@@ -665,9 +665,9 b' dependencies = ['
 
 [[package]]
 name = "python3-sys"
-version = "0.6.0"
+version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b78af21b29594951a47fc3dac9b9eff0a3f077dec2f780ee943ae16a668f3b6a"
+checksum = "b18b32e64c103d5045f44644d7ddddd65336f7a0521f6fde673240a9ecceb77e"
 dependencies = [
  "libc",
  "regex",

rust/hg-cpython/Cargo.toml

@@ -21,13 +21,10 b' python27-bin = ["cpython/python27-sys"]'
 python3-bin = ["cpython/python3-sys"]
 
 [dependencies]
+cpython = { version = "0.7.0", default-features = false }
 crossbeam-channel = "0.4"
 hg-core = { path = "../hg-core"}
 libc = "0.2"
 log = "0.4.8"
 env_logger = "0.7.1"
 stable_deref_trait = "1.2.0"
-
-[dependencies.cpython]
-version = "0.6.0"
-default-features = false