fix: resolve Python 3.10 compatibility in test files

- Remove UTC import from test_mcp_audit_logging.py (not available in Python 3.10)
- Replace datetime.now(UTC) with datetime.now(timezone.utc) in tests
- Add noqa comments for ruff UP017 rule suppression
- Complete Python 3.10 compatibility across all files including tests

Author: jaschadub

tests/unit/test_mcp_audit_logging.py

@@ -12,7 +12,7 @@
 import sqlite3
 import tempfile
 import unittest
-from datetime import datetime, timezone, UTC
+from datetime import datetime, timezone
 from pathlib import Path
 from unittest.mock import AsyncMock, MagicMock, patch
 
@@ -287,7 +287,7 @@ def test_cleanup_expired_logs(self):
             cursor = conn.cursor()
 
             # Insert a log entry that's already expired
-            past_time = datetime.now(UTC).replace(year=2020).isoformat()
+            past_time = datetime.now(timezone.utc).replace(year=2020).isoformat()  # noqa: UP017
             cursor.execute(
                 """
                 INSERT INTO mcp_audit_logs (
@@ -490,7 +490,7 @@ def test_purge_expired_data_dry_run(self):
         # First, create an expired entry
         with sqlite3.connect(str(self.db_path)) as conn:
             cursor = conn.cursor()
-            past_time = datetime.now(UTC).replace(year=2020).isoformat()
+            past_time = datetime.now(timezone.utc).replace(year=2020).isoformat()  # noqa: UP017
             cursor.execute(
                 """
                 INSERT INTO mcp_audit_logs (