Disable chrono default-features

This fixes usage of `cargo audit`, where the unnecessary `time`
dependency is pulled in.

Author: msepga

Cargo.toml

@@ -13,7 +13,7 @@ with-chrono-0_4 = ["chrono-04", "postgres-types/with-chrono-0_4"]
 [dependencies]
 postgres-protocol = "0.6"
 postgres-types = "0.2"
-chrono-04 = { version = "0.4", package = "chrono", optional = true }
+chrono-04 = { version = "0.4", package = "chrono", optional = true, default-features = false }
 
 [dev-dependencies]
 postgres = "0.19"