[cli] Fix panic while running latest deployment command witch -latest flag

[pkrolikowski]

Trying to check latest deployment of a job which has no deployments (no update stanza), nomad fails witch this error

$ nomad job deployments -latest nomad-exporter

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x10c771a]

goroutine 1 [running]:
github.com/hashicorp/nomad/command.formatDeployment(0x0, 0x8, 0xe, 0x0)
	/opt/gopath/src/github.com/hashicorp/nomad/command/deployment_status.go:169 +0x3a
github.com/hashicorp/nomad/command.(*JobDeploymentsCommand).Run(0xc420449880, 0xc420074080, 0x2, 0x2, 0xc4201655f0)
	/opt/gopath/src/github.com/hashicorp/nomad/command/job_deployments.go:138 +0x7b6
github.com/hashicorp/nomad/vendor/github.com/mitchellh/cli.(*CLI).Run(0xc4203eaa20, 0xc4203eaa20, 0x2a, 0x14c84a8)
	/opt/gopath/src/github.com/hashicorp/nomad/vendor/github.com/mitchellh/cli/cli.go:242 +0x229
main.RunCustom(0xc420074060, 0x4, 0x4, 0xc42040f740, 0x0)
	/opt/gopath/src/github.com/hashicorp/nomad/main.go:54 +0xf2d
main.Run(0xc420074060, 0x4, 0x4, 0xc4200001a0)
	/opt/gopath/src/github.com/hashicorp/nomad/main.go:24 +0x56
main.main()
	/opt/gopath/src/github.com/hashicorp/nomad/main.go:20 +0x64

[dadgar]

Awesome thanks for the PR. I am going to merge and add a test!

[github-actions]

I'm going to lock this pull request because it has been closed for 120 days ⏳. This helps our maintainers find and focus on the active contributions.
If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.