Bump mongodb from 3.3.4 to 3.6.4 in /aws-lambda-mongodb-atlas (#107)

Bumps [mongodb](https://github.com/mongodb/node-mongodb-native) from 3.3.4 to 3.6.4.
- [Release notes](https://github.com/mongodb/node-mongodb-native/releases)
- [Changelog](https://github.com/mongodb/node-mongodb-native/blob/3.6/CHANGES_3.0.0.md)
- [Commits](mongodb/node-mongodb-native@v3.3.4...v3.6.4)

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]