Module 3 - FA2 token Error in reference answer due to old syntax

- [Microsoft Windows 10 Home] **System Information**
- [Google Chrome Version 96.0.4664.45] Browser type and version
- [Windows 10.0.19043 Build 19043] OS type and version
- [> Error: invalid flag usage: initial-cast Error > Click on "Show Answer" for reference. ]
- [Error message flagged, even through the answer is exactly same as reference] **Describe the bug**

Steps to reproduce the behavior:

1. Go to https://cryptocodeschool.in/tezos/academy/module-03/chapter-03
2. Fill in contract.py, with reference answer
3. Click check button
4. There is error flagged in console
> Error: invalid flag usage: initial-cast Error
> Click on "Show Answer" for reference.

[Reference answer need to be updated based on latest syntax in FA2 template, so that we can proceed to next session] **Expected behavior**
A clear and concise description of what you expected to happen.

Open the Module 3, Chapter 3 lesson and reproduce the check using the reference answer in contract.py. Compare the answer with the current FA2 template syntax and the console's “invalid flag usage: initial-cast” error. Done means the reference answer validates without that error and allows the learner to continue.

Written by the indexing model from the issue text.