Union parameter not passed in multi-search queries #95

        for model, collection in model_and_collection:
            query.append(
                {
                    "collection": collection.schema_name,
                    "query_by": collection.query_by_fields,
                    "q": q,
                }
            )
        results = client.multi_search.perform(
            {
                "union": True,
                "searches": query,
            }, {
                "per_page": self.paginate_by,
                "page": page_number,
            }
        )

    def perform(
        self,
        search_queries: MultiSearchRequestSchema,
        common_params: typing.Union[MultiSearchCommonParameters, None] = None,
    ) -> MultiSearchResponse:
        """
        Perform a multi-search operation.

        This method allows executing multiple search queries in a single API call.
        It processes the search parameters, sends the request to the Typesense API,
        and returns the multi-search response.

        Args:
            search_queries (MultiSearchRequestSchema):
                A dictionary containing the list of search queries to perform.
                The dictionary should have a 'searches' key with a list of search
                    parameter dictionaries.
            common_params (Union[MultiSearchCommonParameters, None], optional):
                Common parameters to apply to all search queries. Defaults to None.

        Returns:
            MultiSearchResponse:
                The response from the multi-search operation, containing
                    the results of all search queries.
        """
        stringified_search_params = [
            stringify_search_params(search_params)
            for search_params in search_queries.get("searches")
        ]
        search_body = {"searches": stringified_search_params}

        response: MultiSearchResponse = self.api_call.post(
            MultiSearch.resource_path,
            body=search_body,
            params=common_params,
            as_json=True,
            entity_type=MultiSearchResponse,
        )
        return response