Fix typo in fn name

I don't believe that getSpeechServerFactories is a function. I believe it is called get_speech_server_factories. If I try to run Orca 46.1 main with Spiel integration, it crashes due to the fact this function does not exist. If I change the function, it works with Spiel with one erroneously thrown error. So it still throws an error saying spiel isn't available for some reason, but it does work with Spiel fine until I run into (#525 (closed)) again upon navigating in Firefox.

I am unclear how to fix this leftover issue since I am not sure what f.__name__[5:] is referring to semantically.

host@computer ~/g/o/_build (main)> orca --replace --speech-system="spiel"
Speech system “spiel” is unavailable (available: speechdispatcherfactory, spiel)

For some reason this error with the function name was not occurring when I had prior issue (#525 (closed)) with Spiel where it crashed due to a missing field and blocked keyboard input. I can still reproduce the issue (#525 (closed)) where the keyboard input is blocked if I close and relaunch firefox and navigate around naviable text fields.

My spiel config is the following for context.

['ai.piper.Speech.Provider', 'Piper']
['amy', ['en_US'], 'audio/x-spiel,format=S16LE,channels=1,rate=22050']

Original error for context:

host@computer ~/g/orca (main) [1]> orca --replace --speech-system="spiel"
Traceback (most recent call last):
  File "/usr/local/bin/orca", line 274, in main
    factories = [f.__name__[5:] for f in manager.getSpeechServerFactories()]
                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'SettingsManager' object has no attribute 'getSpeechServerFactories'. Did you mean: 'get_speech_server_factories'?

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/bin/orca", line 296, in <module>
    sys.exit(main())
             ^^^^^^
  File "/usr/local/bin/orca", line 281, in main
    print(messages.CLI_SPEECH_SYSTEM_ERROR % (args.speech_system, ', '.join(factories)))
                                                                            ^^^^^^^^^
UnboundLocalError: cannot access local variable 'factories' where it is not associated with a value