ci: run Packit on commit events as well

Let's do a Packit build on "commit" events as well, which automagically
enables Packit's OpenScanHub integration [0].

Since OSH runs only on x86_64 Fedora Rawhide builds, let's limit the
scope for the "commit" event adequately; we still do the usual builds
across all supported Fedora releases (and architectures) in PRs.

The OSH integration is still in its experimental stage, but there's a
plan to add SARIF support and integrate it into GitHub's UI (see [1]),
which should make it quite useful.

[0] https://packit.dev/posts/openscanhub-prototype
[1] packit/dashboard#441

.packit.yaml

@@ -15,6 +15,11 @@ upstream_package_name: polkit
 downstream_package_name: polkit
 
 jobs:
+- job: copr_build
+  trigger: commit
+  targets:
+  - fedora-rawhide-x86_64
+
 - job: copr_build
   trigger: pull_request
   targets: