phpipam: Update PVC storage class name

The other day, when I was dealing with the mess that I accidentally
created by letting the *phpipam* MySQL database automaticall upgrade
itself, I attempted to restore from a Longhorn backup to try to get the
database working again.  This did work, but as a side-effect, it changed
the storage class name of the *phpipam-pvc* persistent volume claim from
`longhorn` to `longhorn-static`.  Now, when attempting to apply the
YAML manifest, `kubectl` complains because this field is immutable.  As
such, the manifest needs to be updated to reflect the value set by
Longhorn when the backup was restored and the PVC was recreated.

phpipam/phpipam.yaml

@@ -34,7 +34,7 @@ metadata:
 spec:
   accessModes:
   - ReadWriteOnce
-  storageClassName: longhorn
+  storageClassName: longhorn-static
   resources:
     requests:
       storage: 1Gi