Update golang.org/x/crypto/ssh to patch CVE-2022-27191

[rcjames]

Describe the bug
There is a vulnerability in the version of the crypto/ssh package used in Vault. I have raised this as per the security policy and been informed that this is not exploitable, but as the email mentions "The Vault team also welcomes community contributions" I assumed this was a hint that a PR to update the version might be accepted.

CVE-2022-27191 - GHSA-8c26-wmh5-6g9v