Update gremlint version for the published application

https://tinkerpop.apache.org/gremlint/ shows Gremlin 3.5.2. It should match the most current version that has been released. Currently that would be 3.6.4. The version is taken from package.json and the gremlint version specified there i think. Not sure how this is best resolved per branch, but need to make appropriate adjustments and probably update the dev docs to verify the appropriate version is present on release.