Fix high CPU usage when using the null audio backend

Author: sa-exe

src/NitroSharp.Launcher/ConfigurationReader.cs

@@ -135,7 +135,7 @@ private static void Set(Configuration configuration, KeyValuePair<string, JsonVa
             {
                 "XAUDIO" or "XAUDIO2" => AudioBackend.XAudio2,
                 "OPENAL" or "OPENALSOFT" or "OPENAL SOFT" => AudioBackend.OpenAL,
-                "NULL" or "Null" or "null" or "AUTO" or "Auto" or "auto" => AudioBackend.Null,
+                "NULL" or "Null" or "null" => AudioBackend.Null,
                 _ => null,
             };
         }

src/NitroSharp/Media/NullAudio/NullAudioSource.cs

@@ -50,8 +50,10 @@ private async Task PlayAsync(PipeReader audioData)
         private async Task ConsumeLoop(PipeReader audioData)
         {
             Debug.Assert(_cts is not null);
+            SpinWait spinner = new();
             while (!_cts.IsCancellationRequested)
             {
+                spinner.SpinOnce();
                 ReadResult readResult = await audioData.ReadAsync();
                 audioData.AdvanceTo(readResult.Buffer.End);
             }