Test tweety-ns 2.x ("4.x") and update anything needed

[dgw]

Major update to upstream library, which now supports async (can't use that here) and fixed some glitches. The older 1.x library versions on PyPI won't keep working forever.

No detailed changelog is available, except for commit messages saying there might be breaking changes and instability in the so-called "Update 4.0" (again, annoying that upstream uses different version numbers in commits/source versions and PyPI packages).

[dgw]

Did some preliminary testing. lxml is required for tweety 2.x to function properly, but it isn't required by the package metadata. Filed mahrtayyab/tweety#224 and opened mahrtayyab/tweety#225 to hopefully resolve this soon.

My 'production' bot using 1.x says it can't access Twitter data, though I haven't yet tried updating the plugin/library there.