Migrate to structured logging

src/app.rs

@@ -4,6 +4,7 @@ use iced::{keyboard, window, Subscription};
 use iced_core::{Font, Size, Theme};
 use iced_core::window::Position;
 use iced_core::window::settings::PlatformSpecific;
+use log::info;
 use rusqlite::Connection;
 use crate::data_provider::card_sets::load_sets;
 use crate::data_provider::settings::get_setting;
@@ -15,7 +16,7 @@ use crate::navigation::RootMessage::Keyboard;
 pub const USER_FONT: Font = Font::with_name("Noto Sans JP");
 
 pub fn start() -> iced::Result {
-    println!("Welcome to JapLearn");
+    info!("Welcome to JapLearn");
     iced::application(ScreenState::boot, ScreenState::update, ScreenState::view)
         .window(window_settings())
         .subscription(subscription)