[17.0] partner_firstname: XML declarations in HTML module descriptions are deprecated

[Armitxes]

Module

partner_firstname

Describe the bug

partner_firstname module causes log warning when updated
Log: https://pastebin.com/YNxjThzM

To Reproduce

Affected versions: 17.0

Steps to reproduce the behavior:

1. Update the module with latest odoo 17 sources

Expected behavior
Update without any errors

Additional context
Tested with odoo.sh with the repo implementet as submodule

[github-actions]

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