Remove setup step from build workflow

Dependencies (git, curl, builder user) are now provided by the
custom act_runner image. Only su builder for makepkg remains.

.gitea/workflows/build-and-publish.yaml

@@ -14,14 +14,6 @@ jobs:
   build-and-publish:
     runs-on: moonarch
     steps:
-      - name: Setup build environment
-        run: |
-          pacman -Sy --noconfirm git curl
-
-          # makepkg refuses to run as root — create a build user
-          useradd -m builder
-          echo "builder ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
-
       - name: Build and publish changed packages
         run: |
           git clone http://gitea:3000/nevaforget/moonarch-pkgbuilds.git repo