Windows: Prevent Windows 11 from starting a conhost.exe process for ever calibre worker process

Apparently on modern windows we need DETACHED_PROCESS not
CREATE_NO_WINDOW. Sigh.

See #2111559 (Fetching news, wrong path for conhost.exe)

Author: kovidgoyal

src/calibre/utils/ipc/launch.py

@@ -80,7 +80,7 @@ def windows_creationflags_for_worker_process(priority: str = 'normal') -> int:
         'high'  : subprocess.HIGH_PRIORITY_CLASS,
         'normal': subprocess.NORMAL_PRIORITY_CLASS,
         'low'   : subprocess.IDLE_PRIORITY_CLASS
-    }[priority] | subprocess.CREATE_NO_WINDOW
+    }[priority] | subprocess.DETACHED_PROCESS
 
 
 class Worker: