v0.67.0

What's Changed

• Fix typo in comment. by @iheanyi in https://github.com/planetscale/planetscale-go/pull/132
• Use planetscale-go version as User Agent, also allow users to set custom UAs and headers by @iheanyi in https://github.com/planetscale/planetscale-go/pull/133

Full Changelog: https://github.com/planetscale/planetscale-go/compare/v0.66.0...v0.67.0