Bump redis from 7.2-alpine to 8.6 in /contrib/helm/nginx-declarative-api (#108)

Bumps redis from 7.2-alpine to 8.6.

---
updated-dependencies:
- dependency-name: redis
  dependency-version: '8.6'
  dependency-type: direct:production
...

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Author: dependabot[bot]

contrib/helm/nginx-declarative-api/values.yaml

@@ -142,7 +142,7 @@ redis:
 
   image:
     repository: redis
-    tag: "7.2-alpine"
+    tag: "8.6"
     pullPolicy: IfNotPresent
 
   replicaCount: 1
@@ -440,4 +440,4 @@ ingress:
 networkPolicy:
   enabled: false
   extraIngress: []
-  extraEgress: []
+  extraEgress: []