Fix text generator example

[nskins]

This PR resolves an incompatibility conflict amongst the dependencies in the text generator example. I think we should prevent this in the future by setting each dependency to a specific version. This PR also fixes breaking changes resulting from the updated dependencies.

Summary of changes:

• Update dependencies to latest versions
• Update output sequence to first element of tuple returned by Axon.lstm/2
• Update deprecated Nx function to_batched_list/3 to to_batched/3

[seanmor5]

Thank you!