Update textproc/epubcheck to 1.1
>From Ryo ONODERA in PR pkg/44123

Upstream changes:

- Fix for issue [#83]; version bump to 1.1 RC2
- Correction to unmanifested test for files [#80];
- Support for ISO8601 dates [#56];
- Added test for files added to the <guide> but not in the <manifest> [#45]
- Resolution for [#58] and and [#75]
- Clarified the language around the commonly-encountered Saxon configuration problem.

(gls)