refactor: add logging for successful database connections in main function

cmd/go_migrate/main.go

@@ -56,6 +56,7 @@ func main() {
 			return err
 		}
 
+		log.Info("Successfully connected to sourceDb")
 		return nil
 	})
 
@@ -66,6 +67,7 @@ func main() {
 			return err
 		}
 
+		log.Info("Successfully connected to targetDb")
 		return nil
 	})