chore(helm): switch from Deployment to StatefulSet (#1901)

Jellyseerr is not designed to support multiple concurrently running instances.
To ensure that only one instance can run at any given time we:

- Replace Deployment with StatefulSet: switch from running "at least N pods" to
  "at most N pods".
- Remove replicaCount value: default is 1, we do not want to support more.

charts/jellyseerr-chart/Chart.yaml

@@ -3,7 +3,7 @@ kubeVersion: ">=1.23.0-0"
 name: jellyseerr-chart
 description: Jellyseerr helm chart for Kubernetes
 type: application
-version: 2.6.2
+version: 2.7.0
 appVersion: "2.7.3"
 maintainers:
   - name: Jellyseerr