Minor fixes

Hi, I've made a couple of tweaks:
* dropped unnecessary `Digest::SHA1` dependency (see [RT#69810](https://rt.cpan.org/Public/Bug/Display.html?id=69810) and #4)
* Pod typo fix as per [RT#90007](https://rt.cpan.org/Public/Bug/Display.html?id=90007) (@dsteinbrunner++)
* update repository metadata, so that it would show up nicely on [MetaCPAN](https://metacpan.org/pod/Net::OAuth)

This PR is part of my [advent quest](https://questhub.io/realm/perl/quest/547b4202070ccf750d00010e).

Cheers,
Sergey.