Improve null tolerations for all resources

Add null toleration to definitions.json so that all non-optional resources are now null-tolerant

v1.29.0

Adds v1.29 manifests (but also removes v1.20 and v1.21)

All the json schema completely change with this release to a newer schema version so as to be compatible with the changes that make use of the referencing library (no functional changes have been detected as a result)

v1.28.1

Update to version 1.28.1

v1.25.0

Release of kubernetes-validate for kubernetes 1.25

Python 2 is no longer supported