DEVX-93: fix: force pip upgrade in setup-image to install new dependencies

tests/unit/test_start_docker.py

@@ -272,18 +272,16 @@ class TestMain:
         assert result.exit_code == 0
         mock_start.assert_called_once_with(60)
 
-    @patch("devx.molecule.start_docker.os.environ.get")
     @patch("devx.molecule.start_docker.start_docker_daemon", return_value=True)
-    def test_exports_github_env(self, mock_start: MagicMock, mock_get: MagicMock) -> None:
+    def test_exports_github_env(self, mock_start: MagicMock) -> None:
         """Should write DOCKER_HOST to GITHUB_ENV when available."""
-        mock_get.side_effect = lambda key, default="": (
-            "/tmp/github_env" if key == "GITHUB_ENV" else f"unix://{DOCKER_SOCK}" if key == "DOCKER_HOST" else default
-        )
-        with patch("builtins.open", mock_open()) as mock_file:
-            runner = CliRunner()
-            result = runner.invoke(main, [])
-            assert result.exit_code == 0
-            mock_file.assert_called_with("/tmp/github_env", "a")
+        env = {"GITHUB_ENV": "/tmp/github_env", "DOCKER_HOST": f"unix://{DOCKER_SOCK}"}
+        with patch.dict("os.environ", env, clear=True):
+            with patch("builtins.open", mock_open()) as mock_file:
+                runner = CliRunner()
+                result = runner.invoke(main, [])
+                assert result.exit_code == 0
+                mock_file.assert_called_with("/tmp/github_env", "a", encoding="utf-8")
 
     @patch("devx.molecule.start_docker.os.environ.get", return_value="")
     @patch("devx.molecule.start_docker.start_docker_daemon", return_value=True)