Upgrade Roundcube module to version 1.6.11 with mariadb 10.11.13

[stephdl]

Description

Upgrade Roundcube module to support the latest webmail version

The current Roundcube version is outdated and got a CVE

The goal is to provide a secure, modern webmail experience aligned with upstream development.

Proposed solution

Update the module to use Roundcube to version 1.6.11 with mariadb 10.11.13
Adapt plugin and config handling accordingly to support this upgrade.

Alternative solutions

Stay on the current version, but this limits compatibility and risks security issues due to outdated PHP dependencies.

Additional context

Includes updated plugin handling and config migration. Tested with persistent storage and Redis sessions.

See also

NethServer/ns8-roundcubemail#54

NethServer/ns8-roundcubemail#55

Acknowledgements to upstream Roundcube contributors.

[stephdl]

Target version is ghcr.io/nethserver/roundcubemail:2.0.8-dev.1

what to test:
minor database upgrade
new minor version of roundcubemail

• case 1 direct install : install mail, account provider, roundcubemail, send emails, create address book entries,no issue expected
• case 2 upgrade, install mail, account provider, roundcubemail, send emails, create address book entries, do the upgrade no issue expected