chore: upgrade rmcp to 0.6.0 (#4243)

crates/goose-cli/src/scenario_tests/mock_client.rs

@@ -95,7 +95,7 @@ impl McpClientTrait for MockClient {
         if let Some(handler) = self.handlers.get(name) {
             match handler(&arguments) {
                 Ok(content) => Ok(CallToolResult {
-                    content: Some(content),
+                    content: content,
                     is_error: None,
                     structured_content: None,
                 }),

crates/goose/src/agents/extension_manager.rs

@@ -786,7 +786,7 @@ impl ExtensionManager {
             client_guard
                 .call_tool(&tool_name, arguments, cancellation_token)
                 .await
-                .map(|call| call.content.unwrap_or_default())
+                .map(|call| call.content)
                 .map_err(|e| ErrorData::new(ErrorCode::INTERNAL_ERROR, e.to_string(), None))
         };
 
@@ -1046,7 +1046,7 @@ mod tests {
         ) -> Result<CallToolResult, Error> {
             match name {
                 "tool" | "test__tool" | "available_tool" | "hidden_tool" => Ok(CallToolResult {
-                    content: Some(vec![]),
+                    content: vec![],
                     is_error: None,
                     structured_content: None,
                 }),