ci(vendor-hash): drop vendor-hash-check from SKIP

Once indirect majors are blocked at the Renovate layer, every
remaining Renovate PR that reaches this workflow bumps a module in
place. go.sum changes and vendor content changes together, so the
computed vendorHash moves with go.sum and nix/package.nix is always
staged with a real diff. vendor-hash-check then has both files
staged and exits 0 on its own.

Suppressing it was papering over the symptom of the scenario that
rule was added to eliminate. If the hook ever fires again from
inside this workflow, that is a real invariant break worth
investigating, not something to silence.

Author: cpcloud

.github/workflows/update-vendor-hash.yml

@@ -128,13 +128,6 @@ jobs:
         run: nix build '.#micasa' --no-link -L
 
       - name: Commit and push
-        env:
-          # vendor-hash-check fires when go.sum is staged but nix/package.nix
-          # is not, which is exactly the state when `go mod tidy` reshapes
-          # go.sum without altering vendor contents. The compute step above
-          # already ran the authoritative nix build, so this hook has nothing
-          # to add here.
-          SKIP: vendor-hash-check
         run: |
           git config user.name "github-actions[bot]"
           git config user.email "github-actions[bot]@users.noreply.github.com"