Improve SNMP tests and avoid dns lookups (#166604)

tests/components/snmp/conftest.py

@@ -0,0 +1,13 @@
+"""Conftest for SNMP tests."""
+
+import socket
+from unittest.mock import patch
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def patch_gethostbyname():
+    """Patch gethostbyname to avoid DNS lookups in SNMP tests."""
+    with patch.object(socket, "gethostbyname"):
+        yield