Add migration for threads. Add ability to load .env from wd

migrations/20230511125236_reminder_threads.sql

@@ -0,0 +1,2 @@
+-- Add migration script here
+ALTER TABLE reminders ADD COLUMN `thread_id` BIGINT DEFAULT NULL;

src/main.rs

@@ -90,6 +90,8 @@ async fn _main(tx: Sender<()>) -> Result<(), Box<dyn StdError + Send + Sync>> {
 
     if Path::new("/etc/reminder-rs/config.env").exists() {
         dotenv::from_path("/etc/reminder-rs/config.env")?;
+    } else {
+        dotenv::from_path(".env")?;
     }
 
     let discord_token = env::var("DISCORD_TOKEN").expect("Missing DISCORD_TOKEN from environment");