Shellcheck flags -n as a better replacement -f ! -z

Signed-off-by: Jesse Vincent <jesse@keyboard.io>

bin/kaleidoscope-builder

@@ -545,7 +545,7 @@ fi
 # shellcheck disable=SC1090
 . "${ROOT}/etc/kaleidoscope-builder.conf"
 
-if [ ! -z "${VERBOSE}" ] && [ "${VERBOSE}" -gt 0 ]; then
+if [ -n "${VERBOSE}" ] && [ "${VERBOSE}" -gt 0 ]; then
     ARDUINO_VERBOSE="-verbose"
 else
     ARDUINO_VERBOSE="-quiet"