We want to use PyOxidizer to produce machine native executables
for running Mercurial. This commit starts the process of doing
Under the hood, PyOxidizer uses a "pyembed" crate to manage an
embedded Python interpreter. This crate needs to be vendored
because it relies on a patched version of the rust-cpython
This commit vendors the pyembed crate associated with version
0.3 of PyOxidizer.