[REM] web, project: remove mnmlicons font

The mnmliconsv21 is not used anymore for 7 years (see 660b13bb)

Closes #6382

Part-of: odoo/odoo#109950

debian/copyright

@@ -398,10 +398,6 @@ Files: addons/web/static/fonts/lato/*
 Copyright: 2010-2011 tyPoland Lukasz Dziedzic
 License: SIL-Open-Font-License
 
-Files: addons/web/static/fonts/mnmliconsv21-webfont.*
-Copyright: Carlos Elas
-License: MIT
-
 Files: addons/web/static/src/js/core/mixins.js
 Copyright: 2010-2012 Jeremy Ashkenas
 License: MIT