Update Cargo.toml
Update Cargo.toml

We need to bump version for sdl2 and sdl2-sys, as if we use old versions it will not compile with other libs that use new versions.
I've tested locally - it works fine with sdl2 v0.12.2 and sdl2-sys v0.8.0.
AngryLawyer/rust-sdl2,Cobrand/rust-sdl2,Cobrand/rust-sdl2,andelf/rust-sdl2_gfx,Rust-SDL2/rust-sdl2,vadixidav/rust-sdl2,Rust-SDL2/rust-sdl2,Rust-SDL2/rust-sdl2,Cobrand/rust-sdl2