feat: Add max_output_tokens to Response API

Responses and Completions have a max_output_tokens field. It is currently
missing from the create and response object in Responses API.

This PR fixes it.

fixes: #3562
Signed-off-by: Abhishek Bongale <abhishekbongale@outlook.com>

docs/static/stainless-llama-stack-spec.yaml

@@ -7105,6 +7105,10 @@ components:
           type: string
           description: >-
             (Optional) Truncation strategy applied to the response
+        max_output_tokens:
+          type: integer
+          description: >-
+            (Optional) Upper bound for response tokens generation
         input:
           type: array
           items:
@@ -7459,6 +7463,8 @@ components:
             (Optional) Additional fields to include in the response.
         max_infer_iters:
           type: integer
+        max_output_tokens:
+          type: integer
       additionalProperties: false
       required:
         - input
@@ -7522,6 +7528,10 @@ components:
           type: string
           description: >-
             (Optional) Truncation strategy applied to the response
+        max_output_tokens:
+          type: integer
+          description: >-
+            (Optional) Upper bound for response tokens generation
       additionalProperties: false
       required:
         - created_at