Add GitHub action linters

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Fix groups expansion on umlauts

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Bumps [ezyang/htmlpurifier](https://github.com/ezyang/htmlpurifier) from 4.11.0 to 4.12.0.
- [Release notes](https://github.com/ezyang/htmlpurifier/releases)
- [Changelog](https://github.com/ezyang/htmlpurifier/blob/master/NEWS)
- [Commits](https://github.com/ezyang/htmlpurifier/compare/v4.11.0...v4.12.0

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bump phan/phan from 2.3.0 to 2.4.0

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Update CKEditor to v15

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Fix removed reply to email

Fix HTML handling when switching from plain text to HTML mode

Fix loggin drafts promise errors

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Bump node-sass from 4.12.0 to 4.13.0

Bump eslint-config-prettier from 6.4.0 to 6.5.0

Allow HTML signatures

Fix ckeditor

Fixes https://github.com/nextcloud/mail/issues/1659

 #2148

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Bump psr/log from 1.1.0 to 1.1.1

This reverts commit a3e9fa80.

This reverts commit efee6e44.

This reverts commit ba924f65.

Bumps [phan/phan](https://github.com/phan/phan) from 2.3.0 to 2.4.0.
- [Release notes](https://github.com/phan/phan/releases)
- [Changelog](https://github.com/phan/phan/blob/master/NEWS.md)
- [Commits](https://github.com/phan/phan/compare/2.3.0...2.4.0

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Fix unnecessary line breaks in quoted reply text