Add validate pragma tooling to next v5.x or v6.0 release

[james-toussaint]

🧐 Motivation
Use validate pragma tooling from openzeppelin-confidential-contracts repo.

📝 Details

• validate pragmas openzeppelin-confidential-contracts#129

[arr00]

This will happen automatically with the next release cycle. It was added to master after the release cycle started, and we didn't cherry-pick it. We should keep in mind that although tooling isn't part of the NPM release, it is part of the commit tag, which we use in other repos for tooling symlinks.