ci: Configure Packit propose_downstream job (#293)

When there is a new release of this repo, Packit will fetch
linux-system-roles.spec from the Rawhide branch in Fedora dist-git,
update it (Source lines and %setup will be regenerated) and open a PR in
Fedora Pagure. It will also upload new tarballs to lookaside and update
sources.

The PR will be opened only against Rawhide for now, can be changed in
dist_git_branches.

documentation:
https://packit.dev/docs/configuration/#propose_downstream
https://packit.dev/docs/fedora-releases-guide/

Taking inspiration from
linux-system-roles/auto-maintenance#233

.packit.yaml

@@ -0,0 +1,24 @@
+downstream_package_name: ansible-collection-microsoft-sql
+
+specfile_path: ansible-collection-microsoft-sql.spec
+
+files_to_sync:
+  - ansible-collection-microsoft-sql.spec
+  - src: CHANGELOG.md
+    dest: CHANGELOG.md
+
+upstream_project_url: https://github.com/linux-system-roles/mssql
+
+actions:
+  post-upstream-clone:
+    - "wget https://src.fedoraproject.org/rpms/ansible-collection-microsoft-sql/raw/rawhide/f/ansible-collection-microsoft-sql.spec -O ansible-collection-microsoft-sql.spec.in"
+    - "wget https://src.fedoraproject.org/rpms/ansible-collection-microsoft-sql/raw/rawhide/f/ansible-packaging.inc -O ansible-packaging.inc"
+    - "wget https://raw.githubusercontent.com/linux-system-roles/auto-maintenance/main/generate_spec_sources.py -O generate_spec_sources.py"
+    - "wget https://raw.githubusercontent.com/linux-system-roles/auto-maintenance/main/generate_rpm_changelog.py -O generate_rpm_changelog.py"
+    - "./generate_spec_sources.py ansible-collection-microsoft-sql.spec.in ansible-collection-microsoft-sql.spec"
+  changelog-entry: "./generate_rpm_changelog.py"
+jobs:
+  - job: propose_downstream
+    trigger: release
+    dist_git_branches:
+      - fedora-all