chore(deps): update index.docker.io/sourcegraph/grafana docker tag to v6.3.3 (#1154)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [index.docker.io/sourcegraph/grafana](https://sourcegraph.com/)
([source](https://redirect.github.com/sourcegraph/sourcegraph)) | minor
| `6.0.0` -> `6.3.3` |

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docker-compose/docker-compose.yaml

@@ -470,7 +470,7 @@ services:
   # 'GF_SERVER_ROOT_URL='https://grafana.example.com'
   grafana:
     container_name: grafana
-    image: 'index.docker.io/sourcegraph/grafana:6.0.0@sha256:e40236d0143d0735ff87374afce95b878b8cde448ef65cfdc7008056a03097e8'
+    image: 'index.docker.io/sourcegraph/grafana:6.3.3@sha256:2f68b9b1542e7d75459d983b606d2fdd1c11a75610464e3d7a6ced4f3ac474bf'
     cpus: 1
     mem_limit: '1g'
     volumes: