ci: add valkey service container

Author: thearchitector

.github/workflows/ci.yaml

@@ -9,6 +9,17 @@ jobs:
         python-version: ['3.11', '3.12', '3.13']
         os: [ubuntu-latest, macOS-latest, windows-latest]
 
+    services:
+      valkey:
+        image: valkey/valkey:alpine
+        ports:
+          - 6379:6379
+        options: >-
+          --health-cmd "valkey-cli ping"
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+
     steps:
       - uses: actions/checkout@v4
       - name: Set up PDM