Fixing dependency for Tensorflow

[casabre]

It seems that pyproject.toml setting for dependencies is somehow not PEP508 compatible

dependencies = [
    'tensorflow>="2.0.0"',
    'numpy',
    'scipy',
    'scikit-learn',
]

It should be

dependencies = [
    'tensorflow>=2.0.0',
    'numpy',
    'scipy',
    'scikit-learn',
]