fix: remove deprecated .aws/sso/cache watcher

[epmog]

What was the problem/requirement? (What/Why)

closes #316

We were watching a folder we no longer care about and due to this, we were emitting an message that made users believe there was something critically wrong with their setup.

What was the solution? (How)

As suggested in the issue, remove the watcher line! There are no other references to this path elsewhere in the code base.

What is the impact of this change?

No more misleading error messages around the sso/cache folder.

How was this change tested?

hatch run fmt
hatch build
hatch run lint
hatch run test

Was this change documented?

N/A

Is this a breaking change?

Nope

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