[Certora] Verify mint and burn

[colin-morpho]

The verification ensures that the Morpho token mint and burn function is compliant with the ERC20 specification. It patches the OZ specification for ERC20 to support the upgradeable version.

Replaces #85

TODO:

• [x] README is updated;
• [x] verification succeed;
• [x] CI is updated.

[colin-morpho]

Related discussion in https://github.com/morpho-org/morpho-token-upgradeable/pull/85#discussion_r1832345549

[QGarchery]

Can you point to the right branch @colin-morpho ? At the moment this is showing a lot of changes

[colin-morpho]

@QGarchery my bad, just changed it.