Fix for parsing failure on some track lines

[LB767]

For some reason, the following line fails to parse when getting tracks
G20 FF 60200 005000 780 383 1239 -4107668 43 14220 24 25 18 123 -10 75 -4 75 -4 16 0 0 L3P 05
when trying to get the checksum value.
Line 411 panics not finding the characters.
It must have to do with formatting hex doing some weird stuff which I have no clue about.
Simplifying this to just get the string works fine since the actual checksum check is commented out anyway, and converting to hex can be done then if needed

[gwbres]

Welcome onboard @LB767 👋 and thanks for your contribution.

I'm mostly focused on my RINEX crate these days, but I'll get back soon with some very interesting CGGTTS ops.
I'll be happy to merge contributions in the meantime

[gwbres]

I think I commented out the checksum verification because I could not find a common ground between the specifications and the examples they provide

[gwbres]

just released a v3.2.2 FYI