cicd: constrain changelog

this commit enforces only tags with a "v4" prefix are included in the
changelog

Signed-off-by: ldelossa <ldelossa@redhat.com>

.github/workflows/prepare-release.yml

@@ -28,7 +28,7 @@ jobs:
           curl -o /tmp/git-chglog -L https://github.com/git-chglog/git-chglog/releases/download/0.9.1/git-chglog_linux_amd64
           chmod u+x /tmp/git-chglog
           echo "creating change log for tag: ${{ github.event.inputs.tag }}"
-          /tmp/git-chglog --next-tag "${{ github.event.inputs.tag }}" -o CHANGELOG.md v4.0.0-alpha.2..
+          /tmp/git-chglog --tag-filter-pattern "v4" --next-tag "${{ github.event.inputs.tag }}" -o CHANGELOG.md v4.0.0-alpha.2..
       - name: Create Pull Request
         uses: peter-evans/create-pull-request@v3.1.2
         with: