[6.15.z] Bump kentaro-m/auto-assign-action from 1.2.6 to 2.0.0 (#13966)

Bump kentaro-m/auto-assign-action from 1.2.6 to 2.0.0 (#13965)

(cherry picked from commit 734f57a)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/auto_assignment.yaml

@@ -15,6 +15,6 @@ jobs:
     if: "!contains(github.event.pull_request.labels.*.name, 'Auto_Cherry_Picked')"
     runs-on: ubuntu-latest
     steps:
-      - uses: kentaro-m/auto-assign-action@v1.2.6
+      - uses: kentaro-m/auto-assign-action@v2.0.0
         with:
           configuration-path: ".github/auto_assign.yml"