Describe the bug

It appears the < character is not escaped in HTML notifications.
The < character does not show and causes problems after it.

Version
v0.48.05

How did you install?

Docker

To Reproduce

Steps to reproduce the behavior:

1. Set notification to HTMLcolor and set an email notification
2. Set notification body to {{diff_full}}
3. changes on https://changedetection.io/CHANGELOG.txt do not show the < character and truncate after it.

on the notification:

0.47.00
The line "Visual Selector - Including <button> (#2686)" becomes - "Visual Selector - Including (#2686)"

0.46.00
The notification is truncated after - UI - Extract it cannot cope with <title>
No further lines are included in the notification.

Expected behavior
The notification body should show the whole {{diff_full}}

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):
Email application: Outlook
Email account: gmail