Be explicit about using Python 3.
Be explicit about using Python 3.

zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools,zsiciarz/rust-ffi-stringtools