bob.learn.em (master branch) requires bob.math >= 3.0.0, which does not exist

Due to default version numbering schemes, the current version of the master branch (bob.math 3.0.0b0) is smaller than bob.math 3.0.0, which is required by bob.learn.em: https://gitlab.idiap.ch/bob/bob.learn.em/blob/master/requirements.txt#L7

Hence, the requirement of bob.learn.em cannot be fulfilled at the moment. Either we release a new version of bob.math, or we reduce the requirements of bob.learn.em.