BUG: Use of deprecated pandas function

[FyZyX]

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Reproducible Example

def scan():
    overview = Overview()
    overview.set_filter(filters_dict={
        'Price': 'Over $15',
        'Average Volume': 'Over 2M',
        'Average True Range': 'Over 1.5',
    })
    return overview.screener_view()

Issue Description

This spits out warnings about using append() as it has been deprecated in favor of concat()

frame.append method is deprecated and will be removed from pandas in a future version.

Expected Behavior

Should not use deprecated method.

Installed Versions

0.14.1