[DOC] LITE Time classifier metrics

[dschrempf]

State that Keras Metrics class objects (and functions) can be used. Also link to the Keras documentation.

Closes #2435

Any other comments?

Maybe this change is also relevant for other Keras-based (tensorflow-based) estimators?

PR checklist

For all contributions

• I've added myself to the list of contributors. Alternatively, you can use the @all-contributors bot to do this for you.
• The PR title starts with either [ENH], [MNT], [DOC], [BUG], [REF], [DEP] or [GOV] indicating whether the PR topic is related to enhancement, maintenance, documentation, bugs, refactoring, deprecation or governance.

[aeon-actions-bot]

Thank you for contributing to aeon

I have added the following labels to this PR based on the title: [ $\color{#F3B9F8}{\textsf{documentation}}$ ].
I have added the following labels to this PR based on the changes made: [ $\color{#BCAE15}{\textsf{classification}}$ ]. Feel free to change these if they do not properly represent the PR.

The Checks tab will show the status of our automated tests. You can click on individual test runs in the tab or "Details" in the panel below to see more information if there is a failure.

If our pre-commit code quality check fails, any trivial fixes will automatically be pushed to your PR unless it is a draft.

Don't hesitate to ask questions on the aeon Slack channel if you have any.

PR CI actions

These checkboxes will add labels to enable/disable CI functionality for this PR. This may not take effect immediately, and a new commit may be required to run the new configuration.

• Run pre-commit checks for all files
• Run mypy typecheck tests
• Run all pytest tests and configurations
• Run all notebook example tests
• Run numba-disabled codecov tests
• Stop automatic pre-commit fixes (always disabled for drafts)
• Disable numba cache loading
• Push an empty commit to re-run CI checks

[hadifawaz1999]

LGTM thanks ! So all of our deep learning models should have this change in DOCs, so am happy to get this in now so we can create an issue for it and link this PR as a base example of what should be done, could you create such issue and close the one you made for LITE ?

[dschrempf]

I just realized, there was a small typo: if -> If. I can create an issue for the other Keras-based classifiers.

Also, pyright (and I guess also mypy) do not understand that one can use keras.metrics.Metric objects, since metric is initialized to "accuray" which is a str. However, I didn't want to add a type hint because it seems they are not used much in aeon.

[MatthewMiddlehurst]

@dschrempf feel free to open an issue. We want to incorporate type hints but theres a lot to go through so they are not required for now. Always welcome though and we can help if they include optional dependencies i.e, tensorflow