switch mp3 to tts, add genserver to app supervisor tree that periodically checks for newly connected devices and plays their associated tts message

test/here_i_am/devices_test.exs

@@ -8,7 +8,7 @@ defmodule HereIAm.DevicesTest do
 
     import HereIAm.DevicesFixtures
 
-    @invalid_attrs %{ip_address: nil, audio: nil}
+    @invalid_attrs %{ip_address: nil, tts: nil}
 
     test "list_devices/0 returns all devices" do
       device = device_fixture()
@@ -21,11 +21,11 @@ defmodule HereIAm.DevicesTest do
     end
 
     test "create_device/1 with valid data creates a device" do
-      valid_attrs = %{ip_address: "some ip_address", audio: "some audio"}
+      valid_attrs = %{ip_address: "some ip_address", tts: "some tts"}
 
       assert {:ok, %Device{} = device} = Devices.create_device(valid_attrs)
       assert device.ip_address == "some ip_address"
-      assert device.audio == "some audio"
+      assert device.tts == "some tts"
     end
 
     test "create_device/1 with invalid data returns error changeset" do
@@ -34,11 +34,11 @@ defmodule HereIAm.DevicesTest do
 
     test "update_device/2 with valid data updates the device" do
       device = device_fixture()
-      update_attrs = %{ip_address: "some updated ip_address", audio: "some updated audio"}
+      update_attrs = %{ip_address: "some updated ip_address", tts: "some updated tts"}
 
       assert {:ok, %Device{} = device} = Devices.update_device(device, update_attrs)
       assert device.ip_address == "some updated ip_address"
-      assert device.audio == "some updated audio"
+      assert device.tts == "some updated tts"
     end
 
     test "update_device/2 with invalid data returns error changeset" do