Add dedicated API permission

[CodeShakingSheep]

Problem

Closes https://github.com/YunoHost-Apps/kimai2_ynh/issues/81 .

Solution

Added dedicated API permission in manifest.toml.

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]

Meow :cat2: