Fed-BioMed v3.5 new release

Fed-BioMed v3.5 is now available. Here are some key new features:

• FedProx optimization scheme support for PyTorch
• model evaluation/validation
• NIFTI and MedNIST datasets
• API documentation
• better VPN/containers support
• etc.

More details about the new features can be found in the Fed-BioMed CHANGELOG.