Upgrade PHP version to 8.3

[CodeShakingSheep]

Problem

PHP 8.3 is more recent than PHP 8.2.

Solution

Upgrade to PHP 8.3 which is officially supported by Roundcube.

Version 1.6 Initial release: 28 July 2022 PHP support: >=7.3 <=8.3

See https://github.com/roundcube/roundcubemail/wiki/Version-History and https://github.com/roundcube/roundcubemail/issues/9339 .

PR Status

• [x] Code finished and ready to be reviewed/tested
• [ ] The fix/enhancement were manually tested (if applicable)

Automatic tests

Automatic tests can be triggered on https://ci-apps-dev.yunohost.org/ after creating the PR, by commenting "!testme", "!gogogadgetoci" or "By the power of systemd, I invoke The Great App CI to test this Pull Request!". (N.B. : for this to work you need to be a member of the Yunohost-Apps organization)

[CodeShakingSheep]

!testme

[yunohost-bot]

:books:

[yunohost-bot]

:v: