Update rustyline requirement from 7.0 to 8.0

Updates the requirements on [rustyline](https://github.com/kkawakam/rustyline) to permit the latest version.
- [Release notes](https://github.com/kkawakam/rustyline/releases)
- [Changelog](https://github.com/kkawakam/rustyline/blob/master/History.md)
- [Commits](kkawakam/rustyline@v7.0.0...v8.0.0)

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

datafusion/Cargo.toml

@@ -54,7 +54,7 @@ arrow = { git = "https://github.com/apache/arrow-rs", rev = "c3fe3bab9905739fdda
 parquet = { git = "https://github.com/apache/arrow-rs", rev = "c3fe3bab9905739fdda75301dab07a18c91731bd", features = ["arrow"] }
 sqlparser = "0.9.0"
 clap = "2.33"
-rustyline = {version = "7.0", optional = true}
+rustyline = {version = "8.0", optional = true}
 paste = "^1.0"
 num_cpus = "1.13.0"
 chrono = "0.4"