fix: env handling for empty allowed origins

Author: zcesur

config/dev.exs

@@ -58,7 +58,7 @@ config :algora, AlgoraWeb.Endpoint,
           |> System.get_env("")
           |> String.split(",")
           |> Enum.map(&String.trim/1) do
-       [] -> false
+       [""] -> false
        origins -> origins
      end),
   code_reloader: true,

config/runtime.exs

@@ -102,7 +102,7 @@ if config_env() == :prod do
             |> System.get_env("")
             |> String.split(",")
             |> Enum.map(&String.trim/1) do
-         [] -> true
+         [""] -> true
          origins -> origins
        end),
     secret_key_base: secret_key_base