Add basic bird config test CI flow

.github/workflows/bird.yml

@@ -0,0 +1,18 @@
+name: Test bird configuration
+on:
+  push:
+  pull_request:
+jobs:
+  amd64:
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install bird2
+        run: |
+          sudo add-apt-repository ppa:cz.nic-labs/bird
+          sudo apt-get update
+          sudo apt-get install -y bird2
+      - name: Test skeleton.conf syntax
+        run: /usr/sbin/bird -c skeleton.conf -p