make version 1.2.6 (#1860)

Author: Kangyi Zhang

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@tensorflow/tfjs-core",
-  "version": "1.2.5",
+  "version": "1.2.6",
   "description": "Hardware-accelerated JavaScript library for machine intelligence",
   "private": false,
   "main": "dist/index.js",

src/version.ts

@@ -1,5 +1,5 @@
 /** @license See the LICENSE file. */
 
 // This code is auto-generated, do not modify this file!
-const version = '1.2.5';
+const version = '1.2.6';
 export {version};