Fix repository metadata for dependabot

[wmitsuda]

I have a dependency to this project in my project and dependabot is configure to generate PRs every time a new version is released.

However, the PR always links the old repo URL: https://github.com/pospi/highlightjs-solidity, which is bad since I always want to check the diff before applying the update.

I guess something was not updated on project or npm configuration.

[joshgoebel]

A PR would be welcome. I think we'd just need to update package.json then rebuild/republish?

@pospi