Final fixes for docker optimisation

Also fixed up error of forgetting to include an await in the main function

Cargo.toml

@@ -2,7 +2,7 @@
 name = "mail_app"
 version = "0.1.0"
 authors = ["Nick Bland"]
-edition = "2021"
+edition = "2018"
 
 [lib]
 path = "src/lib.rs"

src/main.rs

@@ -1,5 +1,4 @@
 use std::net::TcpListener;
-use sqlx::PgPool;
 use sqlx::postgres::PgPoolOptions;
 
 use mail_app::startup::run;
@@ -18,6 +17,7 @@ async fn main() -> std::io::Result<()> {
     let connection_pool = PgPoolOptions::new()
         .connect_timeout(std::time::Duration::from_secs(2))
         .connect(&configuration.database.connection_string())
+        .await
         .expect("Failed to connect to Postgres.");
 
     // Take port from settings file