fix: Set notebook cell timeout to 2 minutes

[matthewfeickert]

• Resolves Model-independent Upper Limits section of Upper Limits notebook failing to execute in CI #60
• Resolves Doc rendering of toys tutorial is broken #13

To allow for long running processes that require actual computation extend the notebook cell timeout from the default 30 seconds to 120 seconds (2 minutes).

• c.f. https://jupyterbook.org/en/stable/customize/config.html

* To allow for long running processes that require actual computation
  extend the notebook cell timeout from the default 30 seconds to 120
  seconds (2 minutes).
   - c.f. https://jupyterbook.org/en/stable/customize/config.html

[matthewfeickert]

It seems like this really hangs on InterpolationCodes.ipynb for some reason.

[matthewfeickert]

reading sources... [ 64%] Toys                                                 
/__w/pyhf-tutorial/pyhf-tutorial/book/Toys.ipynb: Executing notebook using local CWD [mystnb]
/__w/pyhf-tutorial/pyhf-tutorial/book/Toys.ipynb: Executed notebook in 80.70 seconds [mystnb]
reading sources... [ 71%] UpperLimitsTable                                     
/__w/pyhf-tutorial/pyhf-tutorial/book/UpperLimitsTable.ipynb: Executing notebook using local CWD [mystnb]
/__w/pyhf-tutorial/pyhf-tutorial/book/UpperLimitsTable.ipynb: Executed notebook in 80.10 seconds [mystnb]

We could probably drop this to 120 seconds to be safe. Though looks like we're having some issues with the Toys notebook actually converging.

[matthewfeickert]

This extends the time it takes for the CI to run, but I think it is worth if for the time being. We should investigate why the notebooks with IPython widgets take so long to run though

reading sources... [ 21%] InterpolationCodes                                   
/__w/pyhf-tutorial/pyhf-tutorial/book/InterpolationCodes.ipynb: Executing notebook using local CWD [mystnb]
/__w/pyhf-tutorial/pyhf-tutorial/book/InterpolationCodes.ipynb: Executed notebook in 122.74 seconds [mystnb]

reading sources... [ 35%] Modifiers                                            
/__w/pyhf-tutorial/pyhf-tutorial/book/Modifiers.ipynb: Executing notebook using local CWD [mystnb]
/__w/pyhf-tutorial/pyhf-tutorial/book/Modifiers.ipynb: Executed notebook in 122.13 seconds [mystnb]