Use get_running_loop instead of get_event_loop

The latter is deprecated and may not always return the running event loop.

src/prompt_toolkit/application/application.py

@@ -985,7 +985,7 @@ def _called_from_ipython() -> bool:
                 # See whether a loop was installed already. If so, use that.
                 # That's required for the input hooks to work, they are
                 # installed using `set_event_loop`.
-                loop = asyncio.get_event_loop()
+                loop = asyncio.get_running_loop()
             except RuntimeError:
                 # No loop installed. Run like usual.
                 return asyncio.run(coro)