Fix CI on Emacs 30.1

[bbatsov]

@rrudakov I've noticed that the CI is broken on Emacs 30.1, as you've used a function that's not available there. (clojure-ts-mode.el:1131:17: Error: the function ‘treesit-outline--at-point’ is not known to be defined.) Can you please look into this?

(I finally got to updating the CI matrix today)

[rrudakov]

Hi @bbatsov, thanks for updating the CI matrix. I'll definitely take a look.