Replace 3.11-dev with 3.11

[hugovk]

Python 3.11 is now out!

https://discuss.python.org/t/python-3-11-0-final-is-now-available/20291

Also add workflow_dispatch, which gives us a button on the Actions page to manually trigger a build, like Travis CI has, just in case we'll need it.

[coveralls]

Pull Request Test Coverage Report for Build 3332363342

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 31.37%

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Totals
Change from base Build 3313143722:	0.0%
Covered Lines:	655
Relevant Lines:	2088

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💛 - Coveralls

[RouxRC]

Thanks Hugo as always!