<!-- Provide a general summary of your proposed changes in the Title field above -->
### Description
<!-- Describe your changes in detail -->
Python 3.10 was released last week.
Test on Python 3.10 and add the Trove classifier.
### Checklist
<!-- go over following points. check them with an `x` if they do apply, (they turn into clickable checkboxes once the PR is submitted, so no need to do everything at once)
-->
This pull request is:
- [ ] A documentation / typographical error fix
- Good to go, no issue or tests are needed
- [x] A short code fix
- please include the issue number, and create an issue if none exists, which
must include a complete example of the issue. one line code fixes without an
issue and demonstration will not be accepted.
- Please include: `Fixes: #<issue number>` in the commit message
- please include tests. one line code fixes without tests will not be accepted.
- [ ] A new feature implementation
- please include the issue number, and create an issue if none exists, which must
include a complete example of how the feature would look.
- Please include: `Fixes: #<issue number>` in the commit message
- please include tests.
**Have a nice day!**
^ Which checklist option should I use?
Should I do something to trigger/test all the workflows?
Closes: #7179
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/7179
Pull-request-sha: 5df7ff0e0d309301a877314e620fadb6f3f570cb
Change-Id: Ib7ecc0de75f7dffdf05db13563f7be10898e67ba