Fix default value for ingress class name (#278)

charts/influxdb/Chart.yaml

 apiVersion: v1
 name: influxdb
-version: 4.9.13
+version: 4.9.14
 appVersion: 1.8.4
 description: Scalable datastore for metrics, events, and real-time analytics.
 keywords:

charts/influxdb/values.yaml

@@ -169,7 +169,7 @@ ingress:
   tls: false
   # secretName: my-tls-cert # only needed if tls above is true
   hostname: influxdb.foobar.com
-  className: nil
+  className: null
   annotations: {}
     # kubernetes.io/ingress.class: "nginx"
     # kubernetes.io/tls-acme: "true"