Add dependabot and backport action

.github/dependabot.yaml

@@ -0,0 +1,13 @@
+# Automatically open PRs to update outdated deps
+# See https://docs.github.com/en/github/administering-a-repository/enabling-and-disabling-version-updates
+
+version: 2
+updates:
+  # Enable version updates for cargo
+  - package-ecosystem: "cargo"
+    # Look for Cargo `.toml` and `.lock` files in the `root` directory
+    directory: "/"
+    # Check the cargo registry for updates every week
+    schedule:
+      interval: "weekly"
+

.github/workflows/backport.yml

@@ -0,0 +1,17 @@
+name: Backport merged pull request
+on:
+  pull_request_target:
+    types: [closed]
+permissions:
+  contents: write # so it can comment
+  pull-requests: write # so it can create pull requests
+jobs:
+  backport:
+    name: Backport pull request
+    runs-on: ubuntu-latest
+    # Don't run on closed unmerged pull requests
+    if: github.event.pull_request.merged
+    steps:
+      - uses: actions/checkout@v4
+      - name: Create backport pull requests
+        uses: korthout/backport-action@v2