Bump webp version

[MidasLamb]

There is a security advisory for the libwebp-sys that webp uses. It's suggested to upgrade to libwebp-sys 0.9.3, which happens in webp 0.2.6

I license past and future contributions under the dual MIT/Apache-2.0 license,
allowing licensees to choose either at their option.

[MidasLamb]

Seems that this would also raise the MSRV to 1.64, I'm not sure if that's fine?

[fintelia]

In a Cargo.toml version = "0.2.2" actually means "any version 0.2.x where x>=2". Thus, even without this change anyone who runs cargo update will pull in the latest version of webp. And if we published a new version of this crate, users would still need to update to get that newly published version