TST: Use paid runner for aarch64

[pllim]

Requested by @larrybradley in astropy/astropy#16565 (comment) but I wanted to wait and see the cost from astropy alone first before unleashing this to other repos. So please ping me in a few weeks. If you want to wait till end of the year to see how astropy feature freeze would impact things, also acceptable. If you don't ping me, I will likely forget.

Action items:

• Decide if the paid runner has enough money left for another repo.
• Decide if photutils can use it sparingly in a way that is cost effective.
• If yes, then Astropy org admin will have to add photutils to the list of allowed repos for the paid runner.
• Then, photutils maintainer will have to do something like Move aarch64 testing to native runner astropy#17024 to actually use it.

Out of scope: Building aarch64 wheels for release.

[pllim]

@larrybradley , I enabled this runner for photutils. Please see https://github.com/astropy/astropy/blob/f7dc2aaa27fe8f43d1dae3e277d5d7a05e74d35b/.github/workflows/ci_cron_weekly.yml#L175 on example usage. Good luck.

[larrybradley]

Thanks, @pllim! PR: #1893.