Bump serde from 1.0.90 to 1.0.91 (#137)

Bumps [serde](https://github.com/serde-rs/serde) from 1.0.90 to 1.0.91.
- [Release notes](https://github.com/serde-rs/serde/releases)
- [Commits](serde-rs/serde@v1.0.90...v1.0.91)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Cargo.lock

@@ -23,7 +23,7 @@ wasm-bindgen = "0.2.33"
 sha-1 = "0.8.1"
 glutin = { git = "https://github.com/iceiix/glutin", rev = "de52fba20678f3931fba3eb6700774469e48512f" }
 byteorder = "1.2.7"
-serde = "1.0.90"
+serde = "1.0.91"
 serde_json = "1.0.39"
 flate2 = { version = "1.0.7", features = ["rust_backend"], default-features = false }
 zip = { version = "0.5.2", features = ["deflate"], default-features = false }