Update modus-themes to their version 4.2.0

Update modus-themes to their version 4.2.0

* doc/misc/modus-themes.org: Update the manual.

* etc/themes/modus-operandi-tritanopia-theme.el:
* etc/themes/modus-vivendi-tritanopia-theme.el: Add new themes
  optimized for users with blue-yellow color deficiency (tritanopia).

* etc/themes/modus-operandi-deuteranopia-theme.el:
* etc/themes/modus-operandi-theme.el:
* etc/themes/modus-operandi-tinted-theme.el:
* etc/themes/modus-vivendi-deuteranopia-theme.el:
* etc/themes/modus-vivendi-theme.el:
* etc/themes/modus-vivendi-tinted-theme.el: Update theme files.

* etc/themes/modus-themes.el: Update main file to the latest version.

* etc/NEWS: Rephrase the announcement about the new Modus themes to
  also mention the tritanopia-optimized items.

Detailed release notes here:
<https://protesilaos.com/codelog/2023-05-30-modus-themes-4-2-0/>.