remove bluebird from devDependencies

We were using bluebird as a Promise implementation for Node.js versions
that did not provide a native Promise (i.e. Node.js 0.10 & 0.12). There
is no need for that anymore, since Node.js have been shipping native
Promise implementation for years by now.

Signed-off-by: Miroslav Bajtoš <mbajtoss@gmail.com>

package.json

@@ -28,7 +28,6 @@
     "strong-globalize": "^6.0.4"
   },
   "devDependencies": {
-    "bluebird": "~2.9.10",
     "eslint": "^7.7.0",
     "eslint-config-loopback": "^13.1.0",
     "juggler-v3": "file:./deps/juggler-v3",

test/transaction.promise.test.js

@@ -4,9 +4,6 @@
 // License text available at https://opensource.org/licenses/MIT
 
 'use strict';
-if (typeof Promise === 'undefined') {
-  global.Promise = require('bluebird');
-}
 const Transaction = require('loopback-datasource-juggler').Transaction;
 require('./init.js');
 require('should');