Add Additional Smoke Tests for Newer Python Features from `3.9`, `3.10`, `3.11`, and `3.12`

We are largely "safe", now that we've stopped using [astor](https://github.com/berkerpeksag/astor), but we should for completeness add additional smoke tests for features such as:

- [x] [walrus operator](https://docs.python.org/3/whatsnew/3.8.html#assignment-expressions)--> [`PR#51`](https://github.com/exercism/python-representer/pull/51)
- [ ] [positional-only operators](https://docs.python.org/3/whatsnew/3.8.html#positional-only-parameters)
- [ ] [continue statements in finally blocks](https://docs.python.org/3/whatsnew/3.8.html#other-language-changes)
- [x] [union operators for dictionaries](https://docs.python.org/3/library/stdtypes.html#typesmapping) --> [`PR#53`](https://github.com/exercism/python-representer/pull/53)
- [x] [Parenthesized context managers](https://docs.python.org/3/whatsnew/3.10.html#parenthesized-context-managers) --> [`PR#52`](https://github.com/exercism/python-representer/pull/52)
- [ ] [dataclasses](https://docs.python.org/3/whatsnew/3.10.html#dataclasses)
- [ ] [itertools.pairwise()](https://docs.python.org/3/library/itertools.html#itertools.pairwise)
- [ ] [exception groups](https://docs.python.org/3/whatsnew/3.11.html#pep-654-exception-groups-and-except)
- [ ] [exception notes](https://docs.python.org/3/whatsnew/3.11.html#pep-678-exceptions-can-be-enriched-with-notes)