Upgrade minimum supported Python version to 3.11

[SamWilsn]

New pypy landed, we should update to that.

Additionally, we should look at updating our code style (eg. Union[Foo, Bar] -> Foo | Bar).

[Carsons-Eels]

These are some changes I will investigate from Python 3.11 that might affect us or are potentially interesting for improving code quality:

• PEP 673 – Self Type
• PEP 654 – Exception Groups and except*
• PEP 678 – Enriching Exceptions with Notes
• dataclasses
• enum
• hashlib.file_digest
• logging.getLevelNamesMapping
• re Atomic grouping and possessive quantifiers
• string
• shutil.rmtree
• time.sleep
• typing
• Unpacking without parenthesis is now allowed: see bpo-46725
• -P command line option and PYTHONSAFEENV environment variable

This should maybe be moved to a separate issue, as this could greatly impact delivery time for this item if we consider it in scope. I'd also like feedback on the list to narrow it down if any of these are not considered worth pursuing.

[SamWilsn]

Let's keep this issue for just updating the Python version and fixing any regressions. You can make issues for any other improvements you think we should do.