Create tone-test outputs exclusively

tonetest.go

@@ -82,7 +82,7 @@ type AudioFileSaver struct {
 //
 //	ffmpeg -f s16le -ar 48000 -ac 2 -i <file> output.wav
 func NewAudioFileSaver(path string) (*AudioFileSaver, error) {
-	f, err := os.Create(path)
+	f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0600)
 	if err != nil {
 		return nil, err
 	}