I claim the ornamental design for an upper of a footwear article, as shown and described.
FIG. 1 is a side perspective view of an upper of a footwear article;
FIG. 2 is a side view of the upper of a footwear article of FIG. 1; and,
FIG. 3 is a top view of the upper of a footwear article of FIG. 1.
The ornamental design that is claimed is shown in solid lines in the drawings. The broken (dashed) lines shown in the figures are included for the purpose of illustrating environmental elements only and form no part of the claimed design. The dashed/dotted lines in the figures are included to define the bounds of the claimed design but do not form part of the claimed design.