docs: Fix python map function in agent md to include Sequence parame… (#444)

…ter.

*Issue #, if available:*

*Description of changes:*
The python map processor has 4 parameters. Updating Agent.MD to reflect
the 4th parameter


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Author: dhegberg

AGENTS.md

@@ -495,9 +495,10 @@ const allResults = results.getResults();
 **Python:**
 
 ```python
+from collections.abc import Sequence
 from aws_durable_execution_sdk_python.concurrency import MapConfig, CompletionConfig
 
-def process_item(ctx: DurableContext, item: dict, index: int) -> dict:
+def process_item(ctx: DurableContext, item: dict, index: int, items: Sequence[dict]) -> dict:) -> dict:
     return ctx.step(lambda _: process(item), name=f"process-{index}")
 
 results = context.map(