Ensuring the version is a string (YelpArchive#5)

Author: JeffAshton

elastalert/schema.yaml

@@ -206,7 +206,7 @@ properties:
   ### Kibana Discover App Link
   generate_kibana_discover_url: {type: boolean}
   kibana_discover_app_url: {type: string}
-  kibana_discover_version: {enum: ['7.3', '7.2', '7.1', '7.0', '6.8', '6.7', '6.6', '6.5', '6.4', '6.3', '6.2', '6.1', '6.0', '5.6']}
+  kibana_discover_version: {type: string, enum: ['7.3', '7.2', '7.1', '7.0', '6.8', '6.7', '6.6', '6.5', '6.4', '6.3', '6.2', '6.1', '6.0', '5.6']}
   kibana_discover_index_pattern_id: {type: string}
   kibana_discover_columns: {type: array, items: {type: string}}
   kibana_discover_from_timedelta: *timeframe