Update version on pypi to 1.2.18
Looks like a 1.2.18 has been logged in the public docs, but the latest version on pypi is 1.2.16. I've recently had a user upgrade to python 3.10 early, which scuppered the dbus dependency because 1.2.16 uses an import that is disabled for 3.10, but I can't tell them to upgrade to 1.2.18 because it's not on pypi yet.