build: update dependencies

[shoenig]

This PR updates go.mod and hclogvet/go.mod (and sum files). This is necessary to pull in updates to make this library and tool compatible with the go1.18 compiler, which needs the newer stdlibs. Probably more info in golang/go#50558 but I didn't actually read all that.

[sah-d3ll nomad (updates)] $ go version 
go version go1.18.2 linux/amd64

before:

[nomad (main)] $ make check 
==> Linting source code...
==> Linting hclog statements...
hclogvet: internal error: package "bytes" without types was imported from "github.com/hashicorp/nomad"
make: *** [GNUmakefile:162: check] Error 1

after:

[nomad (updates)] $ make check
==> Linting source code...
==> Linting hclog statements...
==> Spell checking website...
(etc)