test(#4999): decode node harness output as utf-8

tests/test_3866_project_context_memory_section.py

@@ -211,6 +211,7 @@ console.log(JSON.stringify({memoryHtml, projectHtml, memoryMode: _memoryMode}));
         [NODE, "-e", script],
         capture_output=True,
         text=True,
+        encoding="utf-8",
         timeout=30,
         check=True,
     )