Bump versions of buf files and update readme

[tstirrat15]

Fixes #80

Description

We vendored the validate.proto file because we had issues with generating a stub. This addresses the problem slightly more directly by letting Buf bring in the validate proto dependency from the source module, rather than us needing to maintain the vendor.

Notes

This also brings in other types from the import, which are functionally bloat, but this provides the simplest build process.

Changes

• (chore) Make the lib only run checks on PR changes
• add include_imports to cause generation of validate_pb.rb
• Remove old vendor files

Testing

Review. See that everything is still green.