Upgrade to latest lts 13.22

[tillydray]

Addresses GH-13

You may need to do stack upgrade before stack build, otherwise you are likely to get errors such as:

Unable to load cabal files for snapshot
...
Unable to parse cabal file for foo

[tillydray]

I forgot to run the tests, just ran them and I get

### Error in:   0:Format:51
user error (Text.Regex.Posix.String died: (ReturnCode 17,"illegal byte sequence"))
Cases: 96  Tried: 96  Errors: 1  Failures: 0

So don't merge this in yet :D

EDIT: this is clearly related to GH-16, which needs to be resolved before we can determine if this PR is safe to merge.

[dino-]

Jason, thank you for contributing this. Sorry it took a long time for me to circle back to these epub-* projects. I would like to hold off on moving the Stackage up for this until I do a pile of work on the underlying library dino-/epub-metadata

[dino-]

Worked on this quite a bit, moved stackage snapshot all the way up to lts-20.12 because I'd like to start using language extensions like OverloadedRecordDot and friends.