decoder: update i_bitspersample

The field i_bytes_per_frame was updated, but not i_bitspersample,
causing an inconsistency leading to a buffer overflow.

Fixes #26930

src/input/decoder.c

@@ -405,6 +405,8 @@ static int aout_update_format( decoder_t *p_dec )
 
         p_dec->fmt_out.audio.i_bytes_per_frame =
             p_owner->fmt.audio.i_bytes_per_frame;
+        p_dec->fmt_out.audio.i_bitspersample =
+            p_owner->fmt.audio.i_bitspersample;
         p_dec->fmt_out.audio.i_frame_length =
             p_owner->fmt.audio.i_frame_length;
     }