ci: add remove-old-pr-docs

Signed-off-by: Kenji Miyake <kenji.miyake@tier4.jp>

.github/workflows/remove-old-pr-docs.yaml

@@ -0,0 +1,20 @@
+name: remove-old-pr-docs
+
+on:
+  pull_request_target:
+    types:
+      - closed
+
+jobs:
+  get-docs-version-name:
+    uses: autowarefoundation/autoware-github-actions/.github/workflows/reusable-get-docs-version-name.yaml@tier4/proposal
+
+  remove-old-pr-docs:
+    uses: autowarefoundation/autoware-github-actions/.github/workflows/reusable-remove-docs.yaml@tier4/proposal
+    needs: get-docs-version-name
+    with:
+      script-ref: tier4/proposal
+      mkdocs-yaml: mkdocs.yaml
+      version-name: ${{ needs.get-docs-version-name.outputs.version-name }}
+    secrets:
+      token: ${{ secrets.GITHUB_TOKEN }}