Allow null from/to in range aggregation (#2863)

Author: pquentin

output/openapi/elasticsearch-openapi.json

@@ -680,15 +680,15 @@ export class AggregationRange {
   /**
    * Start of the range (inclusive).
    */
-  from?: double
+  from?: double | null
   /**
    * Custom key to return the range with.
    */
   key?: string
   /**
    * End of the range (exclusive).
    */
-  to?: double
+  to?: double | null
 }
 
 export class RareTermsAggregation extends BucketAggregationBase {