Update to 1.31

Upstream changes:
1.31  2021-04-21

- Try to match more PerlIO ":layer(args)" in open() or binmode()
  e.g. Spreadsheet::ParseODS uses ":gzip(none)";

  Thanks, @shawnlaffan, for the suggestion (cf. PR #12)

- XML::Twig::XPath needs either XML::XPathEngine or XML::XPath
  XML::Twig may use URI if present

- Moo may use Class::XSAccessor if present

- Fixes #10 "Support IUP.pm Module"

1.30  2021-01-13

- change bugtracker to GitHub issues

- guard against trailing slashes for paths in @INC

- interprete more common "use lib" idioms

(wen)