CI: add test workflow for troubleshooting

.github/workflows/manual-test.yml

@@ -0,0 +1,29 @@
+name: Manually test draft release creation
+
+on:
+  - workflow_dispatch
+
+jobs:
+  create-release:
+    runs-on: ubuntu-22.04
+    environment:
+      name: pypi
+      url: https://pypi.org/p/release_feed_mediola
+    permissions:
+      id-token: write
+    steps:
+      # Checking out just to make `gh release create` work.
+      # Using `gh release create --repo` on its own would yield
+      # an `HTTP 403: Resource not accessible by integration` error.
+      - name: Check out source tree
+        uses: actions/checkout@v3
+
+      - name: Create draft release
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+        run: |
+          set -ex
+          VERSION="v0.123.4.5.6-test"
+          gh release create "v${VERSION}" \
+            --draft --generate-notes \
+            --target 4c9d087ca4480bb5a862a49d88ce15e79bf20963