Bump sdl2 and sdl2-sys versions
Bump sdl2 and sdl2-sys versions

Machtan/rust-sdl2_ttf,vadixidav/rust-sdl2,Cobrand/rust-sdl2,Rust-SDL2/rust-sdl2,Rust-SDL2/rust-sdl2,Cobrand/rust-sdl2,Rust-SDL2/rust-sdl2,andelf/rust-sdl2_ttf,AngryLawyer/rust-sdl2,Cobrand/rust-sdl2