fix: stable tag on schedule

[befanyt]

Fix a typo to match for stable weekly tag.

Today scheduled run where it missed the stable tag because of checking for "scheduled" instead of "schedule" https://github.com/ublue-os/bluefin/actions/runs/11762641102/job/32765731717#step:14:26

Should fix https://github.com/ublue-os/bluefin/issues/1918

And you probably want a manual rebuild today of stable images, because it missed the scheduled one.

[m2Giles]

check failed due to ostree.linux not being matched on beta.

[befanyt]

I should have checked for other occurrences; sorry for that. Thanks for the great work @m2Giles!