Toolset 2.10.0 released

[Alex Cabal]

Upgrade with `pipx upgrade standardebooks`

Changelog:

## General

- Fix Python 3.10 compatibility

- Require that ebooks with many translators use 'various_translators' in
the S.E. identifier

## se add-file

- Correctly list dramatis-personae as a file type

## se build

- Fix `srcset` to include full image path. Thanks to Vince Rice

## se build-manifest

- Correctly add accessibility metadata based on images and `alt` text

## se build-spine

- Sort in hierarchical order based on `data-parent` attributes. Thanks
to Gijs van Tulder

## se build-svg-titles

- Add command. Thanks to Gijs van Tulder

## se clean

- Move SVG `<title>` element to top. Thanks to Robin Whittleton

## se find-unusual-characters

- Handle characters unicodedata doesn't. Thanks to Vince Rice

- Handle characters with no unicode name in plain mode. Thanks to Vince Rice

## se lint

- Add x-022, fractions in SVG viewBox. Thanks to Vince Rice

- Fix crash in t-002

- Tweak x-022 message

- Improve t-008

- Fix crash in t-009

- Add s-030, `<em>` outside of quotation marks

## se make-url-safe

- Remove leading dashes

## se modernize-spelling

- Fix a regex

- Various additions