Change type on --wait-for-ready to int

[Adoni5]

Adds type to wait-for-ready argument - clearly I hadn't tested it because recently because I get!

Traceback (most recent call last):
  File "/home/adoni5/miniforge3/envs/readfish/bin/readfish", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/home/adoni5/Projects/readfish/src/readfish/_cli_base.py", line 61, in main
    raise SystemExit(args.func(parser, args, extras))
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/adoni5/Projects/readfish/src/readfish/entry_points/targets.py", line 549, in run
    read_until_client = RUClient(
                        ^^^^^^^^^
  File "/home/adoni5/Projects/readfish/src/readfish/_read_until_client.py", line 73, in __init__
    self.wait_for_minknow_folder(self.timeout)
  File "/home/adoni5/Projects/readfish/src/readfish/_read_until_client.py", line 186, in wait_for_minknow_folder
    if seconds_waited > timeout:
       ^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: '>' not supported between instances of 'int' and 'str'

This PR fixes that