Add an empty dependencies.json to avoid the implicit QtQuick dependency.

Task-number: QTBUG-70264
Change-Id: I67b0f8cee04d3cd255c9df3c9bc7caf79ffdf9a9
Reviewed-by: Jesus Fernandez <Jesus.Fernandez@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>