fix mispell

build/lib/task.js

@@ -32,7 +32,7 @@ async function _doExecute(task) {
     // Always invoke as if it were a callback task
     return new Promise((resolve, reject) => {
         if (task.length === 1) {
-            // this is a calback task
+            // this is a callback task
             task((err) => {
                 if (err) {
                     return reject(err);