Fix anyio.to_thread.run_sync usage for Windows subprocess calls

The run_sync method doesn't accept keyword arguments directly.
Wrap subprocess.run calls in lambda functions to fix the TypeError.

Author: felixweinberger

src/mcp/client/stdio/__init__.py

@@ -259,22 +259,24 @@ async def _kill_process_tree_windows(pid: int) -> None:
     # Use taskkill with /T flag to kill the process tree
     # Note: shell=True is needed on Windows for taskkill to work properly
     result = await anyio.to_thread.run_sync(
-        subprocess.run,
-        ["taskkill", "/F", "/T", "/PID", str(pid)],
-        capture_output=True,
-        shell=True,
-        check=False,
+        lambda: subprocess.run(
+            ["taskkill", "/F", "/T", "/PID", str(pid)],
+            capture_output=True,
+            shell=True,
+            check=False,
+        )
     )
 
     # If taskkill failed, try without /T flag as a fallback
     # This handles the case where the process might have already exited
     if result.returncode != 0:
         await anyio.to_thread.run_sync(
-            subprocess.run,
-            ["taskkill", "/F", "/PID", str(pid)],
-            capture_output=True,
-            shell=True,
-            check=False,
+            lambda: subprocess.run(
+                ["taskkill", "/F", "/PID", str(pid)],
+                capture_output=True,
+                shell=True,
+                check=False,
+            )
         )