Bumps [sshpk](https://github.com/joyent/node-sshpk) from 1.13.1 to 1.15.2. **This update includes security fixes.**
- [Release notes](https://github.com/joyent/node-sshpk/releases)
- [Commits](https://github.com/joyent/node-sshpk/compare/v1.13.1...v1.15.2)
Signed-off-by: dependabot[bot] <support@dependabot.com>