Add .j2 suffix for template files

app/templates/auth/email/reset_password.txt.j2

@@ -0,0 +1,13 @@
+Dear {{ user.username }},
+
+To reset your password click on the following link:
+
+{{ url_for('auth.password_reset', token=token, _external=True) }}
+
+If you have not requested a password reset simply ignore this message.
+
+Sincerely,
+
+The Opaque Team
+
+Note: replies to this email address are not monitored.