Release 8.1.2

What's Changed

• Bump systeminformation from 5.18.3 to 5.21.8 in /ui-tests by @dependabot in #3837
• Try to use manager's latexTypesetter if window.MathJax is not defined by @bollwyvl in #3847
• fix: restoring widgets from saved state is broken since v8 in Lab by @mariobuikhuizen in #3866

Full Changelog: 8.1.1...8.1.2