add manual trigger

2.2.0 versioning

skip async DoH tests if no httpx

(cherry picked from commit ec5bee7)

remove obsolete download URL; add 3.9 classifier

update README.md for 2.1.0rc1

2.0.0 versioning

change license badge color

add wheel

doc->doco to avoid make confusion with doc directory

fix epydoc params for idna_codec