use config file instead of argument options

crates/crawler/src/config.rs

@@ -8,7 +8,7 @@ pub struct Mysql {
     pub host: String,
     pub password: String,
     pub port: u16,
-    pub user: String,
+    pub username: String,
 }
 
 #[derive(Debug, Deserialize)]

crates/crawler/src/main.rs

@@ -30,7 +30,7 @@ fn main() -> Result<()> {
     let db = mysql::Database::pool(
         &config.mysql.host,
         config.mysql.port,
-        &config.mysql.user,
+        &config.mysql.username,
         &config.mysql.password,
         &config.mysql.database,
     )?;