Bump version to 1.21

Author: dderevjanik

build/manifest.json

@@ -7,7 +7,7 @@
     "48": "icon48.png",
     "128": "icon128.png"
   },
-  "version": "1.20",
+  "version": "1.21",
   "author": "Daniel Derevjanik <daniel.derevjanik@gmail.com>",
   "offline_enabled": true,
   "browser_action": {
@@ -53,4 +53,4 @@
     "backgroundScript": "backgroundScriptsAPIBridge.js",
     "contentScript": "contentScriptsAPIBridge.js"
   }
-}
+}