Audio: Correct usage of miniaudio's dynamic rate adjustment.

This affects pitch shifting. The output rate is being modified with
ma_data_converter_set_rate(), but then that value is being used in the
computation of the output rate the next time SetAudioBufferPitch() which
results in a cascade. The correct way to do this is to use an anchored
output rate as the basis for the calculation after pitch shifting. In
this case, it's the device's sample rate that acts as the anchor.

src/raudio.c

@@ -723,7 +723,7 @@ void SetAudioBufferPitch(AudioBuffer *buffer, float pitch)
         // Note that this changes the duration of the sound:
         //  - higher pitches will make the sound faster
         //  - lower pitches make it slower
-        ma_uint32 outputSampleRate = (ma_uint32)((float)buffer->converter.sampleRateOut/pitch);
+        ma_uint32 outputSampleRate = (ma_uint32)((float)AUDIO.System.device.sampleRate/pitch);
         ma_data_converter_set_rate(&buffer->converter, buffer->converter.sampleRateIn, outputSampleRate);
 
         buffer->pitch = pitch;