add libretranslate as an experimental app; add libretranslate to mastodon; update deps

[jessebot]

Add LibreTranslate to the experimental apps:

apps:
  libre_translate:
    description: |
      📖 [link=https://libretranslate.com/]libretranslate[/link] is a self-hosted translation tool.
    enabled: false
    init:
      enabled: true
    argo:
      # secret keys to provide for the argocd secret plugin app, none by default
      secret_keys:
        hostname: ""
      # git repo to install the Argo CD app from
      repo: https://github.com/small-hack/argocd-apps
      # path in the argo repo to point to. Trailing slash very important!
      path: libretranslate/app_of_apps/
      # either the branch or tag to point at in the argo repo above
      revision: main
      # kubernetes cluster to install the k8s app into, defaults to Argo CD default
      cluster: https://kubernetes.default.svc
      # namespace to install the k8s app in
      namespace: libretranslate
      # recurse directories in the provided git repo
      directory_recursion: false
      # source repos for Argo CD App Project (in addition to argo.repo)
      project:
        name: libretranslate
        source_repos:
          - https://small-hack.github.io/libretranslate-helm-chart
        destination:
          # automatically includes the app's namespace and argocd's namespace
          namespaces:
            - libretranslate

Also added a couple of new parameters for mastodon to use libretranslate:

apps:
  mastodon:
    init:
      values:
        # api key for mastodon to do translations through libretranslate
        libretranslate_api_key:
          value_from:
            env: MASTODON_LIBRETRANSLATE_API_KEY
    argo:
      # secrets keys to make available to Argo CD ApplicationSets
      secret_keys:
        # endpoint for libretranslate translations
        libretranslate_hostname: ""