Replace ${SHELL} with "$SHELL" to fix SC2086 (shellcheck)

ufetch-openbsd

@@ -10,7 +10,7 @@ os="$(uname -sr)"
 kernel="$(uname -v)"
 uptime="$(uptime | awk -F, '{sub(".*up ",x,$1);print $1}' | sed -e 's/^[ \t]*//')"
 packages="$(ls -d /var/db/pkg/* | wc -l | sed -e 's/^[ \t]*//')"
-shell="$(basename ${SHELL})"
+shell="$(basename "$SHELL")"
 
 if [ -z "${WM}" ]; then
 	if [ "${XDG_CURRENT_DESKTOP}" ]; then