Update type annotation for DBAPI Cursor's executemany()

Update type annotation for DBAPI Cursor's executemany()

### Description
As per https://groups.google.com/g/sqlalchemy/c/DkyffAgDmwM, fixes an issue with the DBAPI cursor's executemany() type signature.

### Checklist

This pull request is:

- [x] A documentation / typographical / small typing error fix
	- Good to go, no issue or tests are needed
- [ ] 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!**

Closes: #10644
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/10644
Pull-request-sha: 0a1fe849b54e35cd5e417da79556dc94be3a0abc

Change-Id: I3af344f052a2f306876a528c528b1bf9cc0bdaa6
(cherry picked from commit 55bf2bf971cda82c2e3f58e9c211c74c3a6394a8)