Update version 5.8.8

[pp-r]

Problem

• A new release is out with eight fixes including two security vulnerabilities in the PluXml administration. https://pluxml.org/article92/pluxml-588-released

Solution

• Update version 5.8.8

PR Status

• [ ] 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)

[pp-r]

!testme

[yunohost-bot]

Fingers crossed!