The ornamental design for an aspirator, substantially as shown and described.
FIG. 1 is a front perspective view of an aspirator showing my new design.
FIG. 2 is a front view of my aspirator.
FIG. 3 is a back view of my aspirator.
FIG. 4 is a right side view of my aspirator.
FIG. 5 is a left side view of my aspirator.
FIG. 6 is a top view of my aspirator; and,
FIG. 7 is a bottom view of my aspirator.
The broken lines shown in FIGS. 1-7 illustrate portions of the aspirator that form no part of the claimed design.
The aspirator is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design.