removed async_trait from deps to use reexport from serenity

Cargo.toml

@@ -10,7 +10,6 @@ tokio = { version = "0.2", features = ["process"] }
 reqwest = { version = "0.10", features = ["rustls-tls"] }
 sqlx = { version = "0.4", default-features = false, features = ["runtime-tokio-rustls", "macros", "mysql", "bigdecimal", "chrono"] }
 regex = "1.4"
-async-trait = "0.1"
 log = "0.4"
 env_logger = "0.8"
 chrono = "0.4"