Make emoji default_manifest a config option

config/config.exs

@@ -102,7 +102,8 @@ config :pleroma, :emoji,
     # Put groups that have higher priority than defaults here. Example in `docs/config/custom_emoji.md`
     Finmoji: ["/finmoji/128px/*-128.png"],
     Custom: ["/emoji/*.png", "/emoji/custom/*.png"]
-  ]
+  ],
+  default_manifest: "https://git.pleroma.social/vaartis/emoji-index/raw/master/index.json"
 
 config :pleroma, :uri_schemes,
   valid_schemes: [

lib/mix/tasks/pleroma/emoji.ex

@@ -9,7 +9,7 @@ defmodule Mix.Tasks.Pleroma.Emoji do
   @moduledoc """
   """
 
-  @default_manifest "https://git.pleroma.social/vaartis/emoji-index/raw/master/index.json"
+  @default_manifest Pleroma.Config.get!([:emoji, :default_manifest])
 
   def run(["ls-packs" | args]) do
     Application.ensure_all_started(:hackney)