maturin 0.14.13 on Rust Cargo

What's Changed

maturin develop now looks for a virtualenv .venv in the current or any parent directory if no virtual environment is active by @konstin in #1462
Add a new generate-ci command to generate CI configuration by @messense in #1456
Deprecate --universal2 in favor of universal2-apple-darwin target by @messense in #1457
Raise an error when Cargo.toml contains removed python package metadata by @messense in #1471
Use extension_name instead of module_name for CFFI extensions in develop mode by @luizirber in #1476

Full Changelog: v0.14.12...v0.14.13