Fix for Elixir 1.18, add parentheses to module_info call

[MeguminSama]

On Elixir 1.18, I was running into the following warning, caused by a function call in gen_registry that didn't have parentheses.

warning: using map.field notation (without parentheses) to invoke function Gateway.Gen.UserSession.module_info() is deprecated, you must add parentheses instead: remote.function()
  (gen_registry 1.3.0) lib/gen_registry.ex:207: GenRegistry.init/1
  (stdlib 6.0.1) gen_server.erl:2057: :gen_server.init_it/2
  (stdlib 6.0.1) gen_server.erl:2012: :gen_server.init_it/6
  (stdlib 6.0.1) proc_lib.erl:329: :proc_lib.init_p_do_apply/3