flutter_auto_update

Upgrade project https://github.com/ehoraizon/auto_update to newest version flutter and graddle

• Release name of the apk file need to be the same name with the packageName : forexample: if android package name is : com.example.flutter_auto_update_example , the release apk name must be : flutter_auto_update_example.apk
• the package name input to fetchGithub must be the repo name.

Fix bug from origin repo

• Add option to add github token
• Fix error on compare versionCode