Add document to allowed cacheable_types for anthropic

Author: marpulli

pydantic_ai_slim/pydantic_ai/models/anthropic.py

@@ -776,7 +776,7 @@ def _add_cache_control_to_last_param(params: list[BetaContentBlockParam], ttl: L
 
         # Only certain types support cache_control
         # See https://docs.anthropic.com/en/docs/build-with-claude/prompt-caching#what-can-be-cached
-        cacheable_types = {'text', 'tool_use', 'server_tool_use', 'image', 'tool_result'}
+        cacheable_types = {'text', 'tool_use', 'server_tool_use', 'image', 'tool_result', 'document'}
         # Cast needed because BetaContentBlockParam is a union including response Block types (Pydantic models)
         # that don't support dict operations, even though at runtime we only have request Param types (TypedDicts).
         last_param = cast(dict[str, Any], params[-1])