fetch-collection-state-job: Use g_auto*

Closes: GNOME/gnome-photos#77
3 jobs for my_first_patch in 19 minutes and 36 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Test
passed #203805
flatpak

00:18:53

 
  Review
passed #203806
review

00:00:43

manual #203807
allowed to fail manual
stop_review