Fix sphinx autodoc warning

[MetRonnie]

Workaround sphinx-doc/sphinx#10151 (comment)

CylcAuthorizer inherits from trailets.Configurable. The problem is:

In their code, they do import typing as t and they call t.Any, t.Dict, etc...

then when I compile my docs I see warnings as

WARNING: py:class reference target not found: t.Any

If there was some way of disabling the autodoc'ing of (just) CylcAuthorizer's params in cylc-doc I would have gone for that, but I couldn't find any way.

Check List

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• No dependency changes
• Tests are not needed
• No CHANGES.md entry needed
• Xtriggers: Doc Fixes cylc-doc#686