feat: base45

[mriise]

fixes #100

[vmx]

Long time no see @mriise! Thanks for the PR.

[vmx]

I first thought the no_std failures were unrelated. But it looks like the base45 is not no_std compatible :-/

[mriise]

It just needs to feature flag alloc.

I was sort of hoping base45 wasn't on the case insensitive list, the crate assumes it to be uppercase (because that's what the rfc says).
This comment is weird but understandable I guess. multiformats/multibase#125 (comment)

I'll just toUpper() before handing it over to the crate. (oh god the camel case has infected me)
:\

[mriise]

@vmx unless we have a user waiting on this, im ok with waiting a bit for no_std to be merged upstream before this gets merged.

[mriise]

merged and updated :)

[vmx]

Thanks!