bump deps, redux
bump deps, redux

This only bumps the regex dependency. The new clap version causes a bump
in unicode-segmentation, which in turn requires a Rust 1.15, which is
above ripgrep's currently supported minimum Rust version of 1.12.

BurntSushi/ripgrep,BurntSushi/ripgrep,BurntSushi/ripgrep,BurntSushi/ripgrep