feat!: upgrade minimum next version to 14.3.0-canary.68 & upgrade react packages, react-toastify

[AlessioGr]

Description

BREAKING:

• The minimum required next version is now 14.3.0-canary.68. This is because we are migrating away from the deprecated experimental.serverComponentsExternalPackages key to experimental.serverExternalPackages, which is not available in older next canaries

• The minimum react and react-dom versions have been bumped to ^18.2.0 or ^19.0.0. This matches the minimum react version recommended by next

• [ ] I have read and understand the CONTRIBUTING.md document in this repository.

Type of change

• [ ] Chore (non-breaking change which does not add functionality)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Change to the templates directory (does not affect core functionality)
• [ ] Change to the examples directory (does not affect core functionality)
• [ ] This change requires a documentation update

Checklist:

• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] Existing test suite passes locally with my changes
• [ ] I have made corresponding changes to the documentation