chore: indicate compatibility with new v4 major`

[danielroe]

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

With Nuxt 4 on the horizon, this updates the module compatibility definition to allow it to be installed on Nuxt v4. (Otherwise Nuxt will indicate the module might not be compatible.)

You can follow this and other changes in nuxt/nuxt#27613 - please feel free to provide feedback as well!

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes (if not applicable, please state why)

[Baroshem]

Thanks for this @danielroe ! Merging right now :)