chore: revert qemu workflow/do not change packer handling there

Author: samrose

.github/workflows/qemu-image-build.yml

@@ -91,7 +91,7 @@ jobs:
           make init
           GIT_SHA=${{github.sha}}
           export PACKER_LOG=1
-          sudo nix run github:supabase/postgres/${GIT_SHA}#packer -- build -var "git_sha=${GIT_SHA}" -var-file="common-nix.vars.pkr.hcl" qemu-arm64-nix.pkr.hcl
+          packer build -var "git_sha=${GIT_SHA}" -var-file="common-nix.vars.pkr.hcl" qemu-arm64-nix.pkr.hcl
 
       - name: Grab release version
         id: process_release_version