ci: schedule bot PR monitoring (#257)

Calls the shared monitor-bot-pr workflow from go-openapi/ci-workflows
once a day. The workflow detects bot PRs (dependabot or organization
bot) that have auto-merge enabled but have stalled because the branch
fell behind master, and unblocks them by asking for a rebase (a
"@dependabot rebase" comment, or "gh pr update-branch --rebase" for
organization bot PRs).

Signed-off-by: Frédéric BIDON <fredbi@yahoo.com>
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: fredbi

.github/workflows/monitor-bot-pr.yml

@@ -0,0 +1,17 @@
+name: Monitor bot PRs
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '18 6 * * *'
+
+permissions:
+  contents: read
+
+jobs:
+  monitor-pr:
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: go-openapi/ci-workflows/.github/workflows/monitor-bot-pr.yml@ff87261e2ba4b6a01b2b03bf2738b078e064c8c5 # v0.3.0
+    secrets: inherit