Update dendrite.yaml.j2

roles/custom/matrix-dendrite/templates/dendrite/dendrite.yaml.j2

@@ -355,7 +355,7 @@ sync_api:
   # Configuration for the full-text search engine.
   search:
     # Whether or not search is enabled.
-    enabled: {{ matrix_dendrite_syncapi_search_enabled }}
+    enabled: {{ matrix_dendrite_syncapi_search_enabled|to_json }}
     # The path where the search index will be created in.
     index_path: "/matrix-media-store-parent/searchindex"
     # The language most likely to be used on the server - used when indexing, to