Do not make RelMe metadata provider optional.

There's really no sound reason to turn this off anyway.

config/config.exs

@@ -455,7 +455,6 @@ config :pleroma, Pleroma.Web.Metadata,
   providers: [
     Pleroma.Web.Metadata.Providers.OpenGraph,
     Pleroma.Web.Metadata.Providers.TwitterCard,
-    Pleroma.Web.Metadata.Providers.RelMe,
     Pleroma.Web.Metadata.Providers.Feed
   ],
   unfurl_nsfw: false

lib/pleroma/web/metadata.ex

@@ -7,7 +7,8 @@ defmodule Pleroma.Web.Metadata do
 
   def build_tags(params) do
     providers = [
-      Pleroma.Web.Metadata.Providers.RestrictIndexing
+      Pleroma.Web.Metadata.Providers.RestrictIndexing,
+      Pleroma.Web.Metadata.Providers.RelMe,
       | Pleroma.Config.get([__MODULE__, :providers], [])
     ]