[#1] Only parse .js files in umzug migration.

As pointed out in the issue, it's not guaranteed that Node will only
pick *.js - depending on where it's launched and in which state.

This will mean that db migrations can no longer be applied while
developing, but it's a good compromise when weighted against consistent
ease of use.

src/db/Migrations.ts

@@ -9,7 +9,7 @@ class Migrations {
       storage: new SequelizeStorage({ sequelize: db }),
       context: db.getQueryInterface(),
       migrations: {
-        glob: '**/db/migrations/*.*s',
+        glob: '**/db/migrations/*.js',
       },
       logger: console,
     }) as Umzug;