ci(packit): build RPMs on PRs for c10s

- Added a copr_build job triggered on pull requests, targeting
centos-stream-10

Signed-off-by: Joshua Locash <jlocash@redhat.com>

Author: jlocash

.packit.yaml

@@ -12,3 +12,9 @@ files_to_sync:
 upstream_package_name: virt-who
 # downstream (Fedora) RPM package name
 downstream_package_name: virt-who
+
+jobs:
+  - job: copr_build
+    trigger: pull_request
+    targets:
+      - centos-stream-10