Bump natsio/jetstream-controller in /helm/charts/nack

Bumps natsio/jetstream-controller from 0.11.0 to 0.12.0.

---
updated-dependencies:
- dependency-name: natsio/jetstream-controller
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

helm/charts/nack/values.yaml

@@ -7,7 +7,7 @@ jetstream:
   enabled: true
   image:
     repository: natsio/jetstream-controller
-    tag: 0.11.0
+    tag: 0.12.0
     pullPolicy: IfNotPresent
     # registry: docker.io