The ornamental design for a gazebo, as shown and described.
FIG. 1 is a side view of a gazebo showing my new design with round posts, wherein the view from the opposite side of the gazebo is identical.
FIG. 2 is another side view of the gazebo, rotated by 90 degrees relative to FIG. 1, the view from the opposite side of the gazebo being identical.
FIG. 3 is a top perspective view of the gazebo.
FIG. 4 is a top plan view of the gazebo.
FIG. 5 is a side view of a variation of the gazebo showing my new design with square posts, wherein the view from the opposite side of the gazebo is identical.
FIG. 6 is another side view of the variation of the gazebo, rotated by 90 degrees relative to FIG. 5, the view from the opposite side of the gazebo being identical.
FIG. 7 is a top perspective view of the variation of the gazebo; and,
FIG. 8 is a top plan view of the variation of the gazebo.
The broken lines depict portions of the gazebo that form no part of the claimed design.