The ornamental design for a swiveladapter for faucets, as shown and described.
FIG. 1 is a front elevational view of a swivel adapter for faucets in an unswiveled position showing my new design, which is also representative of a rear elevational view, a left-side elevational view, and a right-side elevational view;
FIG. 2 is a bottom plan view thereof;
FIG. 3 is a top plan view thereof; and,
FIG. 4 is a top perspective view thereof, showing the adapter in a swiveled position.
The broken lines in the drawings are for illustrative purposes only and form no part of the claimed design.