[idna] Bump unicode-normalization to 0.1.9

[ashthespy]

With unicode-rs/unicode-normalization#37 landing, this should help with compilation times and sizes (#557)

[SimonSapin]

As far as I understand this PR is not necessary. A dependency declaration of unicode-normalization = "0.1.5" in Cargo means “Any 0.1.x version, where x >= 5”. So when building a project that doesn’t have a Cargo.lock file, Cargo will already pick the most recent matching version. If Cargo.lock already exists and specifies an older version, you can upgrade with cargo update -p unicode-normalization without changing rust-url’s Cargo.toml.

See https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html

[ashthespy]

Your right off course, sorry for the noise!