Fix typing of `partial_reordering`

Fix typing of `partial_reordering`

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The typing of the `partial_reordering` argument of `batch_alter_table` is not correct.

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As stated in the documentation and docstring, the `batch_alter_table()` function expects a list of tuples for the `partial_reordering` argument. The current typing suggests the user to insert a tuple containing Any into the argument, which doesn't align with the docstring.

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This pull request is:

- [ x] A documentation / typographical 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: #1764
Pull-request: https://github.com/sqlalchemy/alembic/pull/1764
Pull-request-sha: f0a0c1a913b93a2c71881e69be83a7888e21bc5e

Change-Id: I1f442df0674e85361234a97aed1d79f58d30214f