Pod::Weaver 4 now uses [-SingleEncoding]

This is the same as [this commit](https://github.com/moose/MooseX-MethodAttributes/commit/b08e2c8b50c92a648ef5eb1418357ba514c5ebea) (yet another drop to my [quest](https://questhub.io/realm/perl/quest/5277f3cc9f567ad56f0000e7)).