Remove unused features from chrono

Author: alexwennerberg

Cargo.toml

@@ -24,7 +24,7 @@ bufstream = "0.1"
 imap-proto = "0.14.0"
 nom = "6.0"
 base64 = "0.13"
-chrono = "0.4"
+chrono = { version = "0.4", default-features = false }
 lazy_static = "1.4"
 
 [dev-dependencies]