fix(tools): IDF_PATH_OLD not found in PowerShell

Closes espressif#15396

Author: mfialaf

tools/activate.py

@@ -43,7 +43,7 @@ def die(msg: str) -> None:
          f'proceeding.'))
 
 try:
-    run([virtualenv_python, os.path.join(idf_path, 'tools', 'export_utils', 'activate_venv.py')] + sys.argv[1:], check=True)
+    run([virtualenv_python, os.path.join(idf_path, 'tools', 'export_utils', 'activate_venv.py')] + sys.argv[1:], check=True, env=os.environ.copy())
 except (OSError, SubprocessError):
     die('\n'.join(['Activation script failed',
                    'To view detailed debug information, set ESP_IDF_EXPORT_DEBUG=1 and run the export script again.']))