Time zone info format detection could be more accurate

[gabriel-vasile]

Right now the check is:

mimetype/internal/magic/binary.go

Line 21 in 222d00f

TzIf = prefix([]byte("TZif"))

This is a lot of room for false positives with this check.

Solution:
https://tools.ietf.org/id/draft-murchison-tzdist-tzif-00.html#rfc.section.3

[n-vr]

Hello @gabriel-vasile!

I am trying to contribute more to open source projects, so I created a PR to fix this issue for you. Ofcourse, feel free to do whatever you please with it.