how to get the nearest date excluding reservations saved in the database?

How to get the nearest date excluding reservations saved in the database?

Reservations always start from Monday and end on Sunday.

I want to get the next week apart from the dates in the table.

Reservation table:

id        start        end
1         2019-12-02   2019-12-08
2         2019-12-23   2019-12-29
...
...

via Chebli Mohamed