Support Python 3.14

[danielhollas]

There was one failing test when I tried to run the test suite with Python 3.14.

I'll see if I can fix it in a reasonable time and if not I'll leave it to somebody more familiar with this codebase.

See logs: https://github.com/aiidateam/disk-objectstore/actions/runs/19059014096/job/54434903766

        # I want to make sure to have generated enough packs, meaning this function is actually testing the behavior
        # This should generated 90 packs
        # NOTE: if you use compress = True, you get many less packs since the data is very compressible! (only 2)
        # So we only test with compress=False
        largest_pack = max(seen_packs)
>       assert largest_pack > 80
E       assert 75 > 80

tests/test_container.py:3116: AssertionError

FAILED tests/test_container.py::test_packs_read_in_order - assert 75 > 80