feat(deps): update alpine docker tag to v3.21

| datasource | package | from | to   |
| ---------- | ------- | ---- | ---- |
| docker     | alpine  | 3.17 | 3.21 |

Author: graphops-renovate[bot]

charts/common/_unittests/layout-tests/single-component/values.yaml

@@ -15,7 +15,7 @@ myComponent:
           containers:
             main:
               name: main
-              image: "alpine:3.17"
+              image: "alpine:3.21"
       replicas: 2
 
 myComponentDefaults: {}