Update serde-big-array requirement from 0.2.0 to 0.3.0

Updates the requirements on [serde-big-array](https://github.com/est31/serde-big-array) to permit the latest version.
- [Release notes](https://github.com/est31/serde-big-array/releases)
- [Commits](https://github.com/est31/serde-big-array/compare/v0.2.0...v0.3.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Cargo.toml

@@ -34,7 +34,7 @@ rand = "0.7.3"
 rustc-hash = "1.1.0"
 serde = "1.0.106"
 serde_derive = "1.0.106"
-serde-big-array = "0.2.0"
+serde-big-array = "0.3.0"
 siphasher = "0.3.3"
 tokio = { version = "0.2.18", features = ["fs", "rt-threaded", "time", "tcp", "udp", "stream", "parking_lot"] }
 toml = "0.5.6"