docker-compose: bump confluentinc/cp-zookeeper in /test (#2301)

Bumps confluentinc/cp-zookeeper from 7.6.1 to 7.9.1.

---
updated-dependencies:
- dependency-name: confluentinc/cp-zookeeper
  dependency-version: 7.9.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

test/compose-schemaregistry.yaml

@@ -1,6 +1,6 @@
 services:
   zookeeper:
-    image: confluentinc/cp-zookeeper:7.6.1
+    image: confluentinc/cp-zookeeper:7.9.1
     environment:
       ZOOKEEPER_CLIENT_PORT: '2181'
       ZOOKEEPER_ADMIN_ENABLE_SERVER: 'false'