Follow-up to apache#275: Bump simple_logger version in Cargo.toml

SimpleLogger is private in v1.6. Bumping its version in Cargo.toml makes
`git pull && carg test` use the new version in an existing checkout
(with an existing Cargo.lock file referencing the old version)

Author: nickolay

Cargo.toml

@@ -32,7 +32,7 @@ serde = { version = "1.0", features = ["derive"], optional = true }
 serde_json = { version = "1.0", optional = true }
 
 [dev-dependencies]
-simple_logger = "1.6"
+simple_logger = "1.9"
 matches = "0.1"
 
 [package.metadata.release]