fix: fix id3v2 sum error

[yinhylin]

No description provided.

[dhowden]

Hey! Thanks for the change.

I think that this is checking for ID3v1 (not v2) hence why it's not considered in SumID3v2 (it's done in SumID3v1).

Is there something else going on here that means you need to implement it there?

[ghost]

@dhowden An mp3 file can have both ID3v1 and ID3v2 tags. This seems to be common on Linux as I've gotten many files that have both. Currently, for files that have both, Sum includes the IDv1 tags in the Sum when it shouldn't.

Also, I believe ID3v2.4 allows the frames to be at the end or beginning of a file, but the library always assumes it's at the beginning.

@yinhylin Thanks for doing this. This is one of the things that I needed. The last consideration is XING headers (like the LAME header) and whether that should be included in the Sum or not.