Add support for packit

This is based on the packit configuration of osbuild.
COPR builds are not enabled because we are building RPMs ourselves
already.

.packit.yaml

@@ -0,0 +1,22 @@
+# https://packit.dev/docs/configuration/
+
+specfile_path: osbuild-composer.spec
+
+synced_files:
+    - osbuild-composer.spec
+    - .packit.yaml
+
+upstream_package_name: osbuild-composer
+downstream_package_name: osbuild-composer
+
+upstream_tag_template: v{version}
+
+actions:
+  get-current-version: bash -c "git describe --tags --abbrev=0 | sed 's|v||'"
+
+jobs:
+- job: propose_downstream
+  trigger: release
+  metadata:
+    dist_git_branches:
+      - fedora-rawhide