Fix compatibility with recent aeon depreciations

[OutragedOctopus]

Reference Issues/PRs

TSML-eval compatibility following aeon 9bacf03 deprecations.

What does this implement/fix? Explain your changes

Update imports to use save_to_ts_file and get_n_cases from collections as detailed in old pre-9bacf03 deprecated annotations

Any other comments?

This is only a fix for aeon main, aeon pip release currently works fine

[tsml-actions-bot]

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