Add Python 3.9, 3.10 and 3.11 and drop 3.7 support

[evamillan]

Python 3.7 reached the end-of-life phase on 2023-06-27 and is no longer supported.

[coveralls]

Pull Request Test Coverage Report for Build 5964552176

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+2.6%) to 85.533%

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Totals
Change from base Build 5778251421:	2.6%
Covered Lines:	7479
Relevant Lines:	8744

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💛 - Coveralls