Merge branch '2.4_branch' of github.com:omry/omegaconf into 2.4_branch

release OmegaConf v2.3.0

OmegaConf 2.2.3 release

OmegaConf 2.2.2 release

OmegaConf 2.2.1 release

bump version to 2.1.2

update NEWS.md and version.py for 2.1.1 release (#778)

2.1.0 release (#745)

2.1.0.rc1 (#713)

Release 2.0.6