Removed condition that is always true (#8862)

Author: radarhere

src/_avif.c

@@ -568,9 +568,7 @@ _encoder_add(AvifEncoderObject *self, PyObject *args) {
     }
 
 end:
-    if (&rgb) {
-        avifRGBImageFreePixels(&rgb);
-    }
+    avifRGBImageFreePixels(&rgb);
     if (!self->first_frame) {
         avifImageDestroy(frame);
     }