Fix tf.random.uniform dtype

[Rohan138]

Why are these changes needed?

tf.random.uniform only supports float16, float32, float64, int32, or int64 as of tensorflow 2.7. This raises a ValueError when using, for example, Discrete actions with dtype=uint8 to save memory, like in the SSD environments.

Using tf.cast() is a little 'hacky', but works until tf supports other dtypes. This fix should probably also be applied with modifications in other places e.g. if component is a Box() and so on.

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[Rohan138]

Closing in favor of #7946 + will need further modifications to fix dtype errors.