Update `vsce` dependency to 2.16.0+ to make `keytar` an optional dependency.

[commiterate]

[email protected] currently locks [email protected] which has keytar as a required dependency.

This breaks builds on Clang systems (e.g. Macs) because keytar's node-gyp build fails due to some invalid C code.

[email protected] moves keytar to an optional dependency instead.

See https://github.com/NixOS/nixpkgs/issues/449650 for more information.

Tasks:

• [ ] Bump vsce to 2.16.0 or higher.
• [ ] Release [email protected].