appdata.xml is missing timestamp

[Bleuzen]

I currently try to update Carla to v2.4.2 on flathub. The build is using the appdata.xml from this repo now. However the build fails with:

builddir/files/share/appdata/studio.kx.carla.appdata.xml: FAILED:
• attribute-missing     : <release> has no timestamp
Validation of files failed
program finished with exit code 1

Your appdata xml releases need a timestamp. For example:

  <releases>
    <release version="2.4.2" date="2022-02-19" />
  </releases>