Pleroma.Gun.ConnectionPool.WorkerSupervisor: fix dialyzer error

lib/pleroma/gun/connection_pool/worker_supervisor.ex:24:guard_fail
The guard clause:

when _ :: true === nil

can never succeed.

lib/pleroma/gun/connection_pool/worker_supervisor.ex

@@ -21,7 +21,7 @@ defmodule Pleroma.Gun.ConnectionPool.WorkerSupervisor do
   def start_worker(opts, retry \\ false) do
     case DynamicSupervisor.start_child(__MODULE__, {Pleroma.Gun.ConnectionPool.Worker, opts}) do
       {:error, :max_children} ->
-        if retry or free_pool() == :error do
+        if Enum.any?([retry, free_pool()], &match?(&1, :error)) do
           :telemetry.execute([:pleroma, :connection_pool, :provision_failure], %{opts: opts})
           {:error, :pool_full}
         else