Sitemap's template isn't working fine with SS5 default trailing slash setup

[silverstripesk]

Module version(s) affected

7.0.0

Description

Sitemap's template is missing slash for styleSheet on SS 5 with default trailing slash setup (new in 5.x)

How to reproduce

just open sitemap.xml on SS 5 website

Possible Solution

No response

Additional Context

No response

Validations

• [X] Check that there isn't already an issue that reports the same bug
• [X] Double check that your reproduction steps work in a fresh installation of silverstripe/installer (with any code examples you've provided)