Fix for 1.9.x: Add vault revision to --version cmd

[mdeggies]

The output of ./vault --version changed since Vault onboarded to CRT/GitHub Actions for building artifacts.

elle: ~/Users/elle/Downloads $ ./vault version
Vault v1.9.1
elle: ~/Users/elle/Downloads $ ./vault version
Vault v1.8.1 (4b0264f28defc05454c31277cfa6ff63695a458d)

This change adds back in the revision string to the version command. Output from the artifacts built on this branch:

elle: ~/Users/elle/Downloads $ ./vault --version
Vault v1.10.0-dev (9e2f21337b47d8ef59f057b6d192d6fde2c5fb19)