Update test_platform.py

Added import dem.core.dev_env as dev_env  to be able to

tests/core/test_platform.py

@@ -4,6 +4,9 @@
 # Unit under test:
 import dem.core.platform as platform
 
+# Unit under test:
+import dem.core.dev_env as dev_env
+
 # Test framework
 import pytest
 from unittest.mock import patch, MagicMock, call, PropertyMock
@@ -25,7 +28,7 @@ def test_dev_env_json_with_invalid_tool_type_expect_success(mock_LocalDevEnvJSON
     test_platform = platform.DevEnvLocalSetup()
 
     # Check expectations
-    assert isinstance(test_platform.local_dev_envs[0], DevEnv)
+    assert isinstance(test_platform.local_dev_envs[0], dev_env.DevEnv)
 
 @patch("dem.core.platform.__supported_dev_env_major_version__", 0)
 @patch("dem.core.platform.LocalDevEnvJSON")