Version 6.4.0 has been built and published. See https://github.com/bndtools/bnd/blob/master/README.md#release for where the released artifacts can be obtained. See https://github.com/bndtools/bnd/wiki/Changes-in-6.4.0 for the release notes.
Version 7.0.0 is now under development. Version 7.0.0 will raise the levels of a number of dependencies such as Java (moving to 17), minimum Gradle version supported, minimum Eclipse version supported.