Bump natsio/nats-box from 0.13.5 to 0.13.8 in /helm/charts/nats (#771)

Bumps natsio/nats-box from 0.13.5 to 0.13.8.

---
updated-dependencies:
- dependency-name: natsio/nats-box
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

helm/charts/nats/values.yaml

@@ -560,7 +560,7 @@ natsBox:
   container:
     image:
       repository: natsio/nats-box
-      tag: 0.13.5
+      tag: 0.13.8
       pullPolicy:
       registry: