firefly-iii: Use volume claim template for redis

Using a volume claim template to define the persistent volume claim for
the Redis pod has two advantages: first, it enables using clustered
Redis, if we decide that becomes necessary, and second, it makes
deleteing and recreating the volume easier in the case of data
corruption.  Simply scale down the StatefulSet to 0, delete the PVC, and
scale the StatefulSet back up.

firefly-iii/redis.yaml

@@ -1,22 +1,3 @@
----
-apiVersion: v1
-kind: PersistentVolumeClaim
-metadata:
-  name: redis
-  namespace: firefly-iii
-  labels:
-    app.kubernetes.io/name: redis
-    app.kubernetes.io/component: redis
-    app.kubernetes.io/instance: firefly-iii
-    app.kubernetes.io/part-of: firefly-iii
-spec:
-  accessModes:
-  - ReadWriteOnce
-  resources:
-    requests:
-      storage: 2Gi
-
----
 apiVersion: v1
 kind: Service
 metadata:
@@ -75,7 +56,7 @@ spec:
           runAsUser: 1000
           runAsGroup: 1000
         volumeMounts:
-        - name: redisdata
+        - name: data
           mountPath: /data
           subPath: data
         - name: tmp
@@ -83,9 +64,21 @@ spec:
       securityContext:
         fsGroup: 1000
       volumes:
-      - name: redisdata
-        persistentVolumeClaim:
-          claimName: redis
       - name: tmp
         emptyDir:
+  volumeClaimTemplates:
+  - apiVersion: v1
+    kind: PersistentVolumeClaim
+    metadata:
+      name: data
+      labels:
+        app.kubernetes.io/name: redis
+        app.kubernetes.io/component: redis
+        app.kubernetes.io/part-of: firefly-iii
+    spec:
+      accessModes:
+      - ReadWriteOnce
+      resources:
+        requests:
+          storage: 2G