chore: update OpenAPI specification from openrouter-web (#43)

Co-authored-by: louisgv <6723574+louisgv@users.noreply.github.com>

Author: mattapperson

.speakeasy/in.openapi.yaml

@@ -4756,14 +4756,12 @@ components:
             rejected_prediction_tokens:
               type: number
         prompt_tokens_details:
-          anyOf:
-            - type: object
-              properties:
-                cached_tokens:
-                  type: number
-                audio_tokens:
-                  type: number
-            - type: 'null'
+          type: object
+          properties:
+            cached_tokens:
+              type: number
+            audio_tokens:
+              type: number
       required:
         - completion_tokens
         - prompt_tokens