LDAP: fix compile warning

Sometimes the compile will emit the following warning, so we'll just avoid it by making it call a function in the LDAP module which will never have this problem.

warning: :GenServer.call/2 is undefined (module :GenServer is not available or is yet to be defined)

lib/pleroma/ldap.ex

@@ -94,6 +94,10 @@ defmodule Pleroma.LDAP do
     :ok
   end
 
+  def bind_user(name, password) do
+    GenServer.call(__MODULE__, {:bind_user, name, password})
+  end
+
   defp connect do
     ldap = Config.get(:ldap, [])
     host = Keyword.get(ldap, :host, "localhost")

lib/pleroma/web/auth/ldap_authenticator.ex

@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.Auth.LDAPAuthenticator do
+  alias Pleroma.LDAP
   alias Pleroma.User
 
   import Pleroma.Web.Auth.Helpers, only: [fetch_credentials: 1]
@@ -19,7 +20,7 @@ defmodule Pleroma.Web.Auth.LDAPAuthenticator do
   def get_user(%Plug.Conn{} = conn) do
     with {:ldap, true} <- {:ldap, Pleroma.Config.get([:ldap, :enabled])},
          {:ok, {name, password}} <- fetch_credentials(conn),
-         %User{} = user <- GenServer.call(Pleroma.LDAP, {:bind_user, name, password}) do
+         %User{} = user <- LDAP.bind_user(name, password) do
       {:ok, user}
     else
       {:ldap, _} ->