fix: Ruff failures

Author: clareliguori

src/python/src/mcp_lambda/client/streamable_http_sigv4.py

@@ -20,8 +20,8 @@
     StreamableHTTPTransport,
     streamablehttp_client,
 )
-from mcp.shared.message import SessionMessage
 from mcp.shared._httpx_utils import McpHttpClientFactory, create_mcp_http_client
+from mcp.shared.message import SessionMessage
 
 
 class SigV4HTTPXAuth(httpx.Auth):

src/python/tests/client/test_streamable_http_sigv4.py

@@ -2,7 +2,6 @@
 Tests for StreamableHTTP Client Transport with AWS SigV4 Signing.
 """
 
-import json
 from datetime import timedelta
 from unittest import mock
 from unittest.mock import AsyncMock, Mock
@@ -161,7 +160,7 @@ def test_init_with_custom_parameters(self, mock_parent_init):
         custom_timeout = 60
         custom_sse_timeout = timedelta(minutes=10)
 
-        transport = StreamableHTTPTransportWithSigV4(
+        StreamableHTTPTransportWithSigV4(
             url=self.url,
             credentials=self.credentials,
             service=self.service,
@@ -187,7 +186,7 @@ def test_sigv4_auth_configuration(self, mock_parent_init):
         """Test that SigV4 auth is configured correctly."""
         mock_parent_init.return_value = None
 
-        transport = StreamableHTTPTransportWithSigV4(
+        StreamableHTTPTransportWithSigV4(
             url=self.url,
             credentials=self.credentials,
             service=self.service,
@@ -299,7 +298,7 @@ async def test_sigv4_auth_configuration(self, mock_streamablehttp_client):
             credentials=self.credentials,
             service=self.service,
             region=self.region,
-        ) as result:
+        ):
             pass
 
         # Get the auth object passed to streamablehttp_client