[BUG] dash bootstrap input component with type number fails to output 0 value

[legendsam]

subject
DBC 0 value

**reproducible example **

import dash_core_components as dcc
import dash_bootstrap_components as dbc
import dash_html_components as html
import dash
from dash.dependencies import Input, Output

app = dash.Dash(__name__) # external_stylesheets=[dbc.themes.BOOTSTRAP])
app.layout = html.Div(
    [
        html.Div("dCc component"),
        dcc.Input(id="dcc", type="number"),
        html.Div("dBc component"),
        dbc.Input(id="dbc", type="number"),
        html.Div("Result"),
        html.Div(id="number-out"),
    ]
)

@app.callback(
    Output("number-out", "children"),
    [Input("dcc", "value"),Input("dbc", "value"),Input("dcc", "n_submit")],
)
def number_render(fval,fval2,btn):
    print(fval,fval2,btn)
    return "DCC : {}".format(fval)+" "+"DBC : {}".format(fval2)

if __name__ == "__main__":
    app.run_server(debug=True)

configuration
dash-auth (1.3.2)
dash-bootstrap-components (0.7.1)
dash-core-components (1.3.1)
dash-html-components (1.0.1)
dash-renderer (1.1.2)
dash-table (4.4.1)

Browser Google Chrome Version 77.0.3865.120 windows
or Firefox 65.0.1 (32 bits) windows

Describe the bug
DBC input returns None when 0 is filled
It's impossible to know that 0 has been entered for DBC input.

Expected behavior
as for DCC input, it should return 0 when 0 is filled

Screenshots

[alexcjohnson]

dash-bootstrap-components is not maintained by Plotly - I would suggest opening this issue at https://github.com/facultyai/dash-bootstrap-components. Thanks!