Move imports to top of file in Unicode test

Consolidate multiprocessing, socket, and time imports at the top of the
file rather than importing them locally within fixtures. The imports
within run_unicode_server remain as they must be available in the
separate process context.

Author: pja-ant

tests/client/test_http_unicode.py

@@ -5,6 +5,9 @@
 (server→client and client→server) using the streamable HTTP transport.
 """
 
+import multiprocessing
+import socket
+import time
 from collections.abc import Generator
 
 import pytest
@@ -144,8 +147,6 @@ async def lifespan(app: Starlette) -> AsyncGenerator[None, None]:
 @pytest.fixture
 def unicode_server_port() -> int:
     """Find an available port for the Unicode test server."""
-    import socket
-
     with socket.socket() as s:
         s.bind(("127.0.0.1", 0))
         return s.getsockname()[1]
@@ -154,10 +155,6 @@ def unicode_server_port() -> int:
 @pytest.fixture
 def running_unicode_server(unicode_server_port: int) -> Generator[str, None, None]:
     """Start a Unicode test server in a separate process."""
-    import multiprocessing
-    import socket
-    import time
-
     proc = multiprocessing.Process(target=run_unicode_server, kwargs={"port": unicode_server_port}, daemon=True)
     proc.start()