[client] Fix - Add RPM metadata required for Red Hat software certification (#7562)

Declare the runtime dependencies, generate the changelog from git tags with
chglog at release time, and ship LICENSE, README.md and an example
/etc/sysconfig/netbird as %license, %doc and %config(noreplace). The unit
generated by "netbird service install" already reads that path via
EnvironmentFile, so post_install.sh is unchanged.

.github/workflows/release.yml

@@ -186,6 +186,11 @@ jobs:
         run: bash shared/management/http/api/generate.sh
       - name: check git status
         run: git --no-pager diff --exit-code
+      - name: Generate RPM changelog from git tags
+        # nfpm embeds changelog.yml into the RPM; Red Hat software certification
+        # requires a changelog. Generated, not committed (see .gitignore).
+        # chglog is a go.mod tool directive, so go.sum pins it and its deps.
+        run: bash release_files/rpm-changelog.sh
       - name: Set up QEMU
         uses: docker/setup-qemu-action@06116385d9baf250c9f4dcb4858b16962ea869c3 #v4.1.0
       - name: Set up Docker Buildx