chore: regenerate Python SDK v0.0.21

Adds support for ChatMessageContentItemFile to enable file attachments in chat messages. Updates OpenAPI spec with file content type, adds overlays for open enums and RSS responses, and regenerates SDK components.

.speakeasy/in.openapi.yaml

@@ -4672,12 +4672,33 @@ components:
             - type
             - video_url
       type: object
+    ChatMessageContentItemFile:
+      type: object
+      properties:
+        type:
+          type: string
+          const: file
+        file:
+          type: object
+          properties:
+            file_data:
+              type: string
+            file_id:
+              type: string
+            filename:
+              type: string
+          required:
+            - file_data
+      required:
+        - type
+        - file
     ChatMessageContentItem:
       oneOf:
         - $ref: '#/components/schemas/ChatMessageContentItemText'
         - $ref: '#/components/schemas/ChatMessageContentItemImage'
         - $ref: '#/components/schemas/ChatMessageContentItemAudio'
         - $ref: '#/components/schemas/ChatMessageContentItemVideo'
+        - $ref: '#/components/schemas/ChatMessageContentItemFile'
       type: object
       discriminator:
         propertyName: type
@@ -4687,6 +4708,7 @@ components:
           input_audio: '#/components/schemas/ChatMessageContentItemAudio'
           input_video: '#/components/schemas/ChatMessageContentItemVideo'
           video_url: '#/components/schemas/ChatMessageContentItemVideo'
+          file: '#/components/schemas/ChatMessageContentItemFile'
     ChatMessageToolCall:
       type: object
       properties: