Hydra since version 1.2 supports backwards compatible upgrades by default
through the use of the
version_base parameter to @hydra.main() and hydra.initialize().
There are three classes of values that the
version_base parameter supports,
given new and existing users greater control of the default behaviors to use.
version_baseparameter is not specified, Hydra 1.x will use defaults compatible with version 1.1. Also in this case, a warning is issued to indicate an explicit
version_baseparameter is None, then the defaults are chosen for the current minor Hydra version. For example for Hydra 1.2, then would imply
version_baseparameter is an explicit version string like "1.1", then the defaults appropriate to that version are used.