2.1.9 version inconsistent?

[PeterJCLaw]

Not sure if this is the usual process for this repo, apologies if so, but I spotted that the commit & tag for 2.1.9 doesn't appear to be on the main (master) branch, unlike the other release tags.

A consequence of this is that the version noted within adminsortable2/__init__.py on master is still 2.1.8.