GitLab

* Fix the bug 'Attempted relative import with no known parent package' when using the bertabs example. Also change the used model from bertabs-finetuned-cnndm, since it seems not be accessible anymore

* Update run_summarization.py
Co-authored-by: Kevin Canwen Xu <canwenxu@126.com>

* all save_pretrained methods mkdir if not os.path.exists

* remove references to old API in docstring - update data processors

* style

* fix tests - better type checking error messages

* better type checking

* include awesome fix by @LysandreJik for #5310

* updated doc and examples