Sanitize ssh kitten shm open error message when sending over tty

This prevents sending attacker controlled data over the tty where it
might end up getting evaled by the shell if the user is doing something
like cat of unsanitized data into the terminal (something that should
never be done).

kittens/ssh/utils.py

@@ -155,7 +155,9 @@ def get_ssh_data(msgb: memoryview, request_id: str) -> Iterator[bytes|memoryview
                 raise ValueError(f'Incorrect request id: {rq_id!r} expecting the KITTY_PID-KITTY_WINDOW_ID for the current kitty window')
         except Exception as e:
             traceback.print_exc()
-            yield f'{e}\n'.encode()
+            import re
+            msg = re.sub(r'[^a-zA-Z0-9 ]+', '_', str(e))
+            yield f'{msg}\n'.encode()
         else:
             yield b'OK\n'
             encoded_data = memoryview(env_data['tarfile'].encode('ascii'))