[fix] filelist_api: NameError: name 'valid_extras'

[rpatterson]

Fixes a crash in the new filelist_api plugin:

Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/flexget/task.py", line 535, in __run_plugin
    result = method(*args, **kwargs)
  File "/usr/lib/python3.8/site-packages/flexget/event.py", line 22, in __call__
    return self.func(*args, **kwargs)
  File "/usr/lib/python3.8/site-packages/flexget/plugins/input/discover.py", line 294, in on_task_input
    return self.execute_searches(config, entries, task)
  File "/usr/lib/python3.8/site-packages/flexget/plugins/input/discover.py", line 134, in execute_searches
    search_results = search.search(task=task, entry=entry, config=plugin_config)
  File "/usr/lib/python3.8/site-packages/flexget/plugin.py", line 127, in wrapped_func
    return func(*args, **kwargs)
  File "/usr/lib/python3.8/site-packages/flexget/components/sites/sites/filelist_api.py", line 102, in search
    params.update({extra: 1 for extra in valid_extras if config.get(extra)})
NameError: name 'valid_extras' is not defined

Done through the GitHub UI, so I haven't tested this, but it sure seems like a simple and obvious fix.

Motivation for changes:

Detailed changes:

Addressed issues:

• Fixes # .

Implemented feature requests:

• Feathub #XX.

Config usage if relevant (new plugin or updated schema):

paste_config_here

Log and/or tests output (preferably both):

paste output here

To Do:

• Stuff..

[liiight]

thanks for this