Minimize external dependencies (wradlib, pandas)

[ladc]

Some new dependencies can be avoided:

• use pysteps io functionality instead of using wradlib's hdf5 reader to avoid an additional dependency on wradlib
• alternative to pandas for a simple datetime parsing

[ladc]

Is the tensorflow_intel package required or should we simply add in the readme that the user can choose an optimized tensorflow implementation?

[Loickemajou]

Is the tensorflow_intel package required or should we simply add in the readme that the user can choose an optimized tensorflow implementation?

Upon testing it, I realised it is not required, I think I should remove it from the setup.