Fix torchvision import

[reuvenperetz]

Pull Request Description:

Fix an issue in importing torchvision during data generation init.
If torch was found and torchvision wasn't - an error was raised even when data generation wasn't used.
This PR fixes this, by checking it torchvision was also found.

In addition, after publishing the nightly package, it's tested that an import can be done after install tf and torch.

Checklist before requesting a review:

• I set the appropriate labels on the pull request.
• I have added/updated the release note draft (if necessary).
• I have updated the documentation to reflect my changes (if necessary).
• All function and files are well documented.
• All function and classes have type hints.
• There is a licenses in all file.
• The function and variable names are informative.
• I have checked for code duplications.
• I have added new unittest (if necessary).