#5 update to latest base64 from industria

I'm porting guile-jwt to use gcrypt (instead of industria's). When doing so I realized that guile-gcrypt's base64 also comes from Industria, however it has a very old version.

guile-jwt needed to allow decoding without padding which Göran Weinholt kindly added. This was around 2018. I just saw he added a few more fixes.

So, this is just an update of base64 using latest and greatest.

Btw, a quick release would be greatly appreciated so I could also publish an updated guile-jwt release... :-D.

Hi!

The change looks good to me, though I'd have one minor request: could you add tests showing decoding without strict padding?

Thanks, and apologies for the delay!

Ludo'.

Hi! Just updated the PR with new tests. Thanks!