Removed Bluebird Promise.reduce from checker.js (#483)

refs TryGhost/Ghost#14882

Co-authored-by: Princi Vershwal <[email protected]>

lib/checker.js

@@ -1,4 +1,3 @@
-const Promise = require('bluebird');
 const _ = require('lodash');
 const requireDir = require('require-dir');
 const debug = require('@tryghost/debug')('checker');
@@ -50,12 +49,12 @@ const check = function checkAll(themePath, options = {}) {
             // set the major version to check
             theme.checkedVersion = versions[version].major;
 
-            return Promise.reduce(_.values(checks), async function (themeToCheck, checkFunction) {
+            return Promise.all(_.values(checks).map(async (checkFunction) => {
                 const now = Date.now();
-                const result = await checkFunction(themeToCheck, options, themePath);
+                const result = await checkFunction(theme, options, themePath);
                 debug(checkFunction.name, 'took', Date.now() - now, 'ms');
                 return result;
-            }, theme);
+            })).then(() => theme);
         })
         .catch((error) => {
             throw new errors.ValidationError({