ci: Remove duplicated nix-quick-install-action

Author: tomasol

.github/workflows/sync-flake-lock.yml

@@ -19,10 +19,6 @@ jobs:
         with:
           fetch-depth: 1
 
-      - uses: nixbuild/nix-quick-install-action@v34
-        with:
-          github_access_token: ${{ secrets.GITHUB_TOKEN }}
-
       - name: Sync flake.lock and rust-toolchain.toml from upstream
         run: |
           curl https://raw.githubusercontent.com/obeli-sk/obelisk/refs/heads/latest/flake.lock -o flake.lock