Tutorial 16 writing error

[dario-coscia]

Describe the bug
In tutorial 16 it is written:

You can define as many conditions as needed, and the model will attempt to minimize all of them simultaneously! You can access the data in various ways:

- `problem.conditions['<condition name>'].input`, `problem.conditions['<condition name>'].output` – Access the input and output data for the specified condition `<condition name>`.
- `problem.input_pts` – Access the input points for all conditions.

But when I try problem.conditions['<condition name>'].output I get an error:

AttributeError: 'TensorInputTensorTargetCondition' object has no attribute 'output'

The corrected behaviour is obtained by problem.conditions['<condition name>'].target.

Currently, this bug is not detected because there are no tests verifying the output property. Even if the tutorial code were updated, the error would not be triggered due to the lack of automated tests for tutorials.

Suggested improvement:

Update the tutorial to use .target instead of .output.

Additional context
Related to #587 we could run the tutorial when building the doc in an automated workflow once per month