ci(mastodon): Integrate mastodon version with renovate

This patch integrates mastodon with renovate in order to
recieve automatic appVersion updates.

charts/mastodon/Chart.yaml

@@ -11,7 +11,8 @@ sources:
     - https://git.shivering-isles.com/shivering-isles/infrastructure-gitops/-/tree/main/charts/mastodon
 
 type: application
-version: 3.0.7
+version: 3.0.8
+# renovate: image=docker.io/tootsuite/mastodon
 appVersion: v3.5.5
 
 dependencies:

charts/mastodon/values.yaml

 image:
-  repository: tootsuite/mastodon
+  repository: docker.io/tootsuite/mastodon
   # https://hub.docker.com/r/tootsuite/mastodon/tags
   #
   # alternatively, use `latest` for the latest release or `edge` for the image