fix: correct position of context in assertion (#196)

Note: this is not a breaking change as it has not been released yet

Author: rhamzeh

docs/openapiv2/apidocs.swagger.json

@@ -1595,7 +1595,7 @@ message Assertion {
 
   // Additional request context that will be used to evaluate any ABAC conditions encountered
   // in the query evaluation.
-  google.protobuf.Struct context = 6;
+  google.protobuf.Struct context = 4 [(grpc.gateway.protoc_gen_openapiv2.options.openapiv2_field) = {example: '{"view_count": 100}'}];
 }
 
 message Assertions {