Feat & Fix(API): Sending emails to users

- Send emails to users when they register or when they reset their
  password.
- Fix `.gitignore` not recoginizing changes in `lib` folder

backend/tests/lib/email.py

@@ -0,0 +1,10 @@
+from pytest import LogCaptureFixture
+from quart import Quart
+
+from backend.lib.email import send_email
+
+
+async def test_send_email(app: Quart, caplog: LogCaptureFixture) -> None:
+    async with app.app_context():
+        await send_email("member@tozo.dev", "Welcome", "email.html", {})
+    assert "Sending email.html to member@tozo.dev" in caplog.text