feat: add client.list_models() method

tests/v1_list_models_test.rs

@@ -0,0 +1,17 @@
+use jrest::expect;
+use mistralai_client::v1::client::Client;
+
+#[test]
+fn test_list_models() {
+    extern crate dotenv;
+
+    use dotenv::dotenv;
+    dotenv().ok();
+
+    let client = Client::new(None, None, None, None);
+
+    let response = client.list_models().unwrap();
+
+    expect!(response.object).to_be("list".to_string());
+    expect!(response.data.len()).to_be_greater_than(0);
+}