Fix sneaky torch dependency in TF example
Thanks to @muellerzr for uncovering this one - the TF image classification example sneakily depended on `torch` because it used `MODEL_FOR_IMAGE_CLASSIFICATION_MAPPING` (which is a dummy if `torch` is unavailable) and called one of the `TrainingArguments` properties that requires `torch`. Made a quick PR to fix it!
_The documentation is not available anymore as the PR was closed or merged._