Cargo git dependency causes slow clone of llvm repo

[ss2165]

If one uses qirlib as a cargo dependency using the git specification,
e.g. in Cargo.toml

qirlib = {path ="https://github.com/qir-alliance/pyqir"}

Cargo attempts to clone llvm-project as a submodule, which is a very large repository, and does not appear to be required for the dependency.

I don't have a good suggested fix, nor do I know if this actually requires fixing, just something I thought was worth being aware of.

Currently my workaround is to clone the repository myself without submodules and have a local path dependency.