Summarization model doesn't work

Yeah. That works with Transformers v4. However, I think it will throw an error with v5. The second half maybe works as-is. (Colab used to run on v4 until recently, but v5 is now the default.)

Since this is simply a Transformers version mismatch, if you run !pip install -U "transformers<5" beforehand and restart the Colab runtime, then the first half of the code should work as well, too.