Check arch in justfile

nix-flake-update.sh

@@ -2,18 +2,9 @@
 
 set -euo pipefail
 
-arch=$(uname -s)
-
 git pull
 update_msg=$(nix flake update 2>&1 | grep -v 'warning:')
-if [[ $arch == "Linux" ]]; then
-  just build-linux
-elif [[ $arch == "Darwin" ]]; then
-  just build-mac
-else
-  echo "Unsupported OS: $arch"
-  exit 1
-fi
+just rebuild
 git add .
 git commit -S -m "nix flake update: $(TZ=UTC date '+%Y-%m-%d %H:%M:%S %Z')