Revert check/renovate to ubuntu-latest — brick-build's image has no Node

brick-build's job container (opensuse/leap:16.0) has no Node.js, and
every step in check/renovate (checkout, setup-ruby, setup-node) is a
JS-based Action that needs it just to start — both runs since the
brick-build switch failed immediately, and deploy never ran because it
depends on check passing. ubuntu-latest is shared with "Gitea Runner on
Cube" (not pinned to this specific machine), but that's fine: only
deploy (a unique label held by just brick's native runner) actually
needs to land on a specific box.

.gitea/workflows/ci.yml

@@ -6,7 +6,15 @@ on:
 
 jobs:
   check:
-    runs-on: brick-build
+    # Not brick-build: that label's job container (opensuse/leap:16.0) has
+    # no Node.js, and every step below (checkout, setup-ruby, setup-node)
+    # is a JS-based Action that needs it to even start — see the run that
+    # failed immediately on 2026-09-12. ubuntu-latest is shared with
+    # "Gitea Runner on Cube" too (not pinned to this machine specifically),
+    # but that's fine here: only deploy (runs-on: brick-host, a unique
+    # label held by just the native runner on brick) actually needs to
+    # land on a specific box.
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4