Update Pymc3_tips_and_heuristics notebook (#4036)

* 1) Fixed: FutureWarnings
2) Updated the notebook to follow the consistent style
3) Use arviz functions directly for plotting on inference data

Fromat the notebook in Black-format

Minor formatting

minor change to execute last cell

Minor text changes.

Renaming file

update the filename in the doc: PyMC3_tips_and_heuristic.ipynb to conditional-autoregressive-model.ipynb

Minos change to remove .ipynb from the name

Move conditional-autoregressive-mode.ipynb from tutorial "How-To" to examples "Gaussian Processes"

* Move the data to csv file (scotland_lips_cancer.csv) instead being hard-coded in conditional-autoregressive-model.ipynb

* Read data from csv file instead of the hardcoded version in notebook.

Author: AmitKus