frappe/webnotes/templates/emails/password_update.html

<h3>Password Update Notification</h3>
<p>Dear {{ first_name }}{% if last_name %} {{ last_name}}{% endif %},</p>
<p>Your password has been updated. Here is your new password: {{ new_password }}</p>
<p>Thank you,<br>
{{ user_fullname }}</p>