decomon release to be compatible with keras 3.0.3

Release v0.2.1 + installation in tutorials updated

decomon release to be compatible with keras 3

Release v0.2.0 + installation in tutorials updated

Release v0.1.1 + installation in tutorials updated

Revert "Replace direct call to get_upper_box by BoxDomain().get_upper"

This reverts commit e98b3c9.
+ add relevant import
+ remove unused imports

Force using tf<2.13 in github actions

This is a temporary patch to avoid having tests much too long (>5hours!)
This is related to this issue: https://github.com/keras-team/keras/issues/18301

Release v0.1.0 + installation in tutorials updated