trossner/fix/op_guests

New functional toggle:

authentication:
  openProject:
    guestAccess:
      # If enabled links pointing to OpenProject no longer redirect to SSO/Keycloak login but show the
      # OpenDesk login screen, where SSO users can click on "Keycloak" to access the SSO login, but guest
      # users can authenticate with their own credentials.
      enabled: false

requires also to include the latest Helm chart version.