使用S3在Heroku上上载Laravel 5.4图像干预

Question

I have created and hosted a website using Heroku which allows users to upload images onto the server, atleast I believe I have. The problem I am encountering currently is

GD Library extension not available with this PHP installation.

I have tried other forums to include the GD files. The page I used for this is How to install GD on Heroku more specifically adding "ext-gd". Preview code of my composer.json is below

{
    "require": {
        "aws/aws-sdk-php": "~2.6",
        "ext-gd": "*" ,
    }
}

However I am starting to believe that the issue could be within my controller rather than my composer. The controller function for image uplods is below:

     public function updateavatar(Request $request, User $user){

if($request->hasFile('avatar')){

    $avatar = $request->file('avatar');
    $filename = time() . '.' . $avatar->getClientOriginalExtension();
    // $destinationPath = public_path('/uploads/avatars/');

    $imageS3 = Image::make($avatar)->resize(300,300);

    Storage::disk("s3")->put($filename, $imageS3->__toString());

    $user = Auth::user();
    $user->avatar = $filename;
    $user->save();

}

This is the form within view.

    <form enctype="multipart/form-data" action="/users/{{$user->id}}/edit" method="POST">
        <label>Update Image</label>
        <input type="file" name="avatar">
        <input type="hidden" name="_token" value="{{csrf_token()}}">
        <input type="submit" value="Submit">
</form>

Any help would be trully usefull. Thanks