Config entry now supports minor versions.
If minor versions differ, but major versions are the same, the integration setup will be allowed to continue even if the integration does not implement async_migrate_entry. This means a minor version bump is backwards compatible, unlike a major version bump which causes the integration to fail setup if the user downgrades HA Core without restoring configuration from backup.
Background
We have been very conservative with versioning config entry data because it breaks downgrading to an older version of Home Assistant Core. This means in most cases, we don't version, and the integrations instead do a kind of soft upgrade where they may, for example, do dict.get on config entry data that was not in an initial version, transform the data during setup etc.
By introducing minor versions similar to that already offered by the storage helper, this pattern is no longer recommended. A bump of the minor version should be done instead whenever the newly added, or otherwise changed, data does not break older versions.
More details can be found in the documentation on config entry migration and in core PR #105749.