rust: Regenerate grammar.rs for unicode escape encoding change
rust: Regenerate grammar.rs for unicode escape encoding change

loganmhb/rust-peg,jsgf/rust-peg,tempbottle/rust-peg,kevinmehall/rust-peg,a-wortman/rust-peg,daramos/rust-peg,a-wortman/rust-peg,jsgf/rust-peg,daramos/rust-peg,kevinmehall/rust-peg,tempbottle/rust-peg,loganmhb/rust-peg