fix: xai doesnt return name in ResponseFormatJsonSchema

Author: vvarma

async-openai/src/types/shared/response_format.rs

@@ -19,7 +19,7 @@ pub struct ResponseFormatJsonSchema {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub description: Option<String>,
     /// The name of the response format. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.
-    pub name: String,
+    pub name: Option<String>,
     /// The schema for the response format, described as a JSON Schema object.
     /// Learn how to build JSON schemas [here](https://json-schema.org/).
     #[serde(skip_serializing_if = "Option::is_none")]