build: bump setup-golang and fix workflow yaml extensions

[shoenig]

Bumps our hashicorp/setup-golang to v2, which itself bumps the official cache and setup-go actions.

Also fixes the file extension of some of our workflows/ files to use .yaml which is technically correct

[lgfa29]

There are a few places that are using .yml that need to be updated as well:

nomad/.github/workflows/release.yml

Line 150 in bb3d222

gh workflow run build.yml --ref ${{ github.ref_name }} --field build-ref=${{ steps.commit-change-push.outputs.build-ref }} --field make-prerelease=false

The Nomad Enterprise repo may have additional ones for the CE->ENT flow, and the release checklist as well 😅

[shoenig]

Hah. Uhh let me just backout the yaml changes; they're beside the point.

[github-actions]

Ember Test Audit comparison

	main	cc34b218d1eb88bedf4052c15e743e171d1401be	change
passes	1540	1540	0
failures	0	0	0
flaky	0	0	0
duration	10m 52s 480ms	10m 54s 958ms	+02s 478ms