[mosquitto] Use appVersion as image tag by default

[ekeih]

Previous title was Update container image in values.yaml to v2.0.14

Description of the change

https://github.com/k8s-at-home/charts/pull/1702 bumped the appVersion but not the actual value.

Benefits

Same as https://github.com/k8s-at-home/charts/pull/1702

Possible drawbacks

Same as https://github.com/k8s-at-home/charts/pull/1702

Applicable issues none

Additional information none

Checklist

• [x] Title of the PR starts with chart name (e.g. [home-assistant])
• [x] Chart version bumped in Chart.yaml according to semver.
• [x] Chart artifacthub.io/changes changelog annotation has been updated in Chart.yaml. See Artifact Hub documentation for more info.
• [x] Variables have been documented in the values.yaml file.

[ekeih]

Thanks for the quick review, I updated the PR with your changes :)