[MNT] tensorflow-addons dependency in networks /_encoder.py

[Cyril-Meyer]

Describe the issue

Linked to #1144 and #1421 : tensorflow-addons dependency need to be removed.
This has probably just been forgotten from the large work in #1421.

        "python_dependencies": ["tensorflow", "tensorflow-addons"],

code ref

Suggest a potential alternative/fix

Remove the tensorflow-addons dependency.

Additional context

Searching for tensorflow-addons and tensorflow_addons with the search engine, I also find something in utils/networks, but I don't know what to do with it.
https://github.com/aeon-toolkit/aeon/blob/6bd3324624dda8835fa17579e6575c470d287c5a/aeon/utils/networks/__init__.py

[Cyril-Meyer]

@aeon-actions-bot assign @Cyril-Meyer