init tesla and updated the http requests in Pleroma.Web.Websub

lib/pleroma/http/connection.ex

@@ -0,0 +1,22 @@
+defmodule Pleroma.HTTP.Connection do
+  @hackney_options [pool: :default]
+
+  @doc """
+  Configure a client connection
+
+  # Returns
+
+  Tesla.Env.client
+  """
+  @spec new(Keyword.t()) :: Tesla.Env.client()
+  def new(opts \\ []) do
+    Tesla.client([], {Tesla.Adapter.Hackney, hackney_options(opts)})
+  end
+
+  # fetch Hackney options
+  #
+  defp hackney_options(opts \\ []) do
+    options = Keyword.get(opts, :adapter, [])
+    @hackney_options ++ options
+  end
+end