fix(smart-contracts): wrong token id after a key was burnt

[clemsos]

Description

This PR fixes a bug in token id assignation after burning a key. As the token id is based on the existing supply of keys and the burn function decrease that supply, the token id calculations should take into account the number of keys that have been burnt.

Issues

Fixes #
Refs #

Checklist:

• 1 PR, 1 purpose: my Pull Request applies to a single purpose
• I have commented my code, particularly in hard-to-understand areas
• I have updated the docs to reflect my changes if applicable
• I have added tests (and stories for frontend components) that prove my fix is effective or that my feature works
• I have performed a self-review of my own code
• If my code involves visual changes, I am adding applicable screenshots to this thread

Release Note Draft Snippet