Bump sshpk from 1.13.1 to 1.16.1

Bumps [sshpk](https://github.com/joyent/node-sshpk) from 1.13.1 to 1.16.1.
- [Release notes](https://github.com/joyent/node-sshpk/releases)
- [Commits](TritonDataCenter/node-sshpk@v1.13.1...v1.16.1)

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Author: dependabot[bot]