Fix tests/test_warp.py

[KumoLiu]

Fixes #7793

Description

The Update() method in ITK is used to trigger the execution of the pipeline. Add it to checks if the output data is up-to-date. If it is not (for example, if the input data or parameters have changed), it will recompute the output.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.

[KumoLiu]

/build