Update docker.io/bitnami/kubectl Docker tag to v1.31.0

Signed-off-by: Renovate Bot <[email protected]>

class/defaults.yml

@@ -80,7 +80,7 @@ parameters:
       kubectl:
         registry: docker.io
         image: bitnami/kubectl
-        tag: '1.25.15'
+        tag: '1.31.0'
     =_crd_version: ${appcat:images:appcat:tag}
 
     namespace: syn-appcat