Update GNN notebook

[zshiqiang]

This PR updates the GNN notebook since some commands are not working for the lastest version of torch_geometric as discussed in issue #166.

Legal Acknowledgement
By contributing to this software project, I agree my contributions are submitted under the BSD license.
I represent I am authorized to make the contributions and grant the license.
If my employer has rights to intellectual property that includes these contributions,
I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.31%. Comparing base (e9e34b4) to head (fc71a69).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #167   +/-   ##
=======================================
  Coverage   90.31%   90.31%           
=======================================
  Files          32       32           
  Lines        2014     2014           
  Branches      316      316           
=======================================
  Hits         1819     1819           
  Misses        123      123           
  Partials       72       72           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.