Fix typos found by codespell

- Typos were found by codespell v1.17.0.dev0 (commit 44fea6d)
- Command used:
  codespell -q 2 \
  -L ba,bloc,blocs,doubleclick,dur,fille,frmat,numer,optin,passtime \
  -L pres,strack,te,tim,tre,uint,whn \
  --skip="*.de-DE.resx,./Bwg*,./Freedb,./MusicBrainz,./ProgressODoom" \
  --skip="./ThirdParty"

CUETools.Codecs.CoreAudio/CoreAudioApi/AudioEndpointVolumeCallback.cs

@@ -46,7 +46,7 @@ namespace NAudio.CoreAudioApi
         {
             //Since AUDIO_VOLUME_NOTIFICATION_DATA is dynamic in length based on the
             //number of audio channels available we cannot just call PtrToStructure 
-            //to get all data, thats why it is split up into two steps, first the static
+            //to get all data, that's why it is split up into two steps, first the static
             //data is marshalled into the data structure, then with some IntPtr math the
             //remaining floats are read from memory.
             //