fix(copr): extract the build target instead of ‹next›

When applying the fixes from the ruff, I didn't realize it calls ‹next›
on the ‹set› which doesn't make sense, so extract that one build target
directly.

Signed-off-by: Matej Focko <[email protected]>

Author: mfocko

packit_service/worker/helpers/build/copr_build.py

@@ -627,9 +627,8 @@ def get_latest_fedora_stable_chroot(self) -> str:
         This is used as a chroot where the Copr source script will be run.
         """
         latest_fedora_stable_chroot = get_aliases().get("fedora-stable")[-1]
-        return next(
-            self.api.copr_helper.get_valid_build_targets(latest_fedora_stable_chroot),
-        )
+        [build_target] = self.api.copr_helper.get_valid_build_targets(latest_fedora_stable_chroot)
+        return build_target
 
     def submit_copr_build(self, script: Optional[str] = None) -> tuple[int, str]:
         """