Add Coronation of His Majesty King Charles III Bank holiday in 2023 to the UK calendar.

[mountinash789]

GOV.UK Press release

• Tests with a significant number of years to be tested for your calendar.
• Changelog amended with a mention describing your changes. Note Please do NOT change the version number here. It's the project maintainers' duty.

[brunobord]

could you please rebase your PR from the latest master branch? It has dropped support for Python 3.6, and added support for Python 3.10/3.11

(if you have any trouble rebasing, please tell me)

[mountinash789]

@brunobord Happy New Year, I have rebased from master. Tests are failing because of the lack of support for 2023 in the Chinese calendar.

[brunobord]

okay, great... and oops, not so great.
There's an ongoing PR here: #728 about China's 2023 holidays.

when it's merged you'll have to (unfortunately) re-rebase against the new master.
sorry about that.

[brunobord]

now you can. :o)

[brunobord]

ok, bear with me for a minute: I'm going to make a release, and then you'll be able to rebase from latest master.

[brunobord]

okay, you're clear to rebase.

Again, sorry for the inconvenience.

[jaraco]

I've merged this feature into the calendra project and released as v7.9.0.