Update gridsome requirement from ^0.5.0 to ^0.6.4 Updates the requirements on [gridsome](https://github.com/gridsome/gridsome) to permit the latest version. - [Release notes](https://github.com/gridsome/gridsome/releases) - [Commits](https://github.com/gridsome/gridsome/compare/gridsome@0.5.0...gridsome@0.6.4) Signed-off-by: dependabot-preview[bot]