Fix test failures on Python 3.14 (#394)

* Fix test failures on Python 3.14

As documented at
https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.get_event_loop,
`get_event_loop` now fails if there is no active event loop. Since there
will never already be one at the top level of a file anyway, explicitly
create a new one every time.

* Reformat with black 2026 style

examples/async_ssl_calculator_client.py

@@ -9,7 +9,6 @@ import socket
 import capnp
 import calculator_capnp
 
-
 this_dir = os.path.dirname(os.path.abspath(__file__))
 
 
@@ -328,5 +327,5 @@ if __name__ == "__main__":
     # Using asyncio.run hits an asyncio ssl bug
     # https://bugs.python.org/issue36709
     # asyncio.run(main(parse_args().host), loop=loop, debug=True)
-    loop = asyncio.get_event_loop()
+    loop = asyncio.new_event_loop()
     loop.run_until_complete(capnp.run(main(parse_args().host)))