add conventional xml.etree.ElementTree import alias

[edhinard]

Summary

Adding a conventional alias for ElementTree. I looked for other conventional aliases in standard library in order to generalize the point, but found none.
There is still an issue with this. It conflicts with N817 CamelCase 'ElementTree' imported as acronym 'ET'. I have to ignore locally:
import xml.etree.ElementTree as ET # noqa: N817
too bad

Test Plan

only test as a lint.flake8-import-conventions.extend-aliases configuration option

[charliermarsh]

You need to add this to CONVENTIONAL_ALIASES in crates/ruff_linter/src/rules/flake8_import_conventions/settings.rs too. We may need to include this in the next minor version.

[charliermarsh]

Thanks. I think this is reasonable to include but it'll have to wait until the next minor version.