Python 3.13: Replace deprecated PyEval_CallObject()

[penguinpee]

The function has been deprecated since Python 3.9 and will be removed
from Python 3.13.

See: https://docs.python.org/3.13/whatsnew/3.13.html#id9

[peterjc]

Do you agree to the licensing terms in the PR template? i.e. to dual-license this and any previous contributions under both the Biopython License Agreement AND the BSD 3-Clause License.

https://github.com/biopython/biopython/blob/master/.github/PULL_REQUEST_TEMPLATE.md

[penguinpee]

I guess that PR template only shows when submitting a PR using the Web UI.

I'm fine with the dual licensing. I don't think it's worth the effort adding myself as a listed contributor.

[peterjc]

That's great. Out of interest, how did you open the PR then?

[penguinpee]

gh pr create --fill using GitHub's command line tool

[peterjc]

@mdehoon can you comment on the Python + C side please?

[mdehoon]

Probably it's OK, but PyEval_CallObject and PyObject_CallObject are not exactly the same.
Perhaps it is time to remove Bio.pairwise2, as it was deprecated in release 1.80, and the next release will be 1.84.

[peterjc]

Given the steady stream of queries about pairwise2, I'd prefer not to remove it quite yet.

The tests seem fine, so we should be OK with this change...