Add auto-merge to Version increment PR (Azure#20072)

Author: chidozieononiwu

eng/pipelines/templates/stages/archetype-python-release.yml

@@ -220,6 +220,7 @@ stages:
                           PRBranchName: increment-package-version-${{ parameters.ServiceDirectory }}-$(Build.BuildId)
                           CommitMsg: "Increment package version after release of ${{ artifact.name }}"
                           PRTitle: "Increment version for ${{ parameters.ServiceDirectory }} releases"
+                          PRLabels: "auto-merge"
                           CloseAfterOpenForTesting: '${{ parameters.TestPipeline }}'
 
   - ${{if and(eq(variables['Build.Reason'], 'Manual'), eq(variables['System.TeamProject'], 'internal'))}}: