bump version

Former-commit-id: 79807c95b68dac8f9c4deb31f92d5c2e3e8a7edd

manifest.json

@@ -8,7 +8,7 @@
 		"64": "extension/ui/resources/icon_64.png",
 		"128": "extension/ui/resources/icon_128.png"
 	},
-	"version": "1.12.20",
+	"version": "1.12.21",
 	"description": "__MSG_extensionDescription__",
 	"content_scripts": [
 		{