fix(ci): initialize pacman keyring in Arch Linux smoke test

Add pacman-key --init before pacman -Syu to fix "no secret key
available to sign with" error when upgrading archlinux-keyring
in the container environment.

Author: andylizf

.github/workflows/build-reusable.yml

@@ -445,6 +445,8 @@ jobs:
     steps:
       - name: Prepare system
         run: |
+          # Initialize pacman keyring to avoid "no secret key available" error
+          pacman-key --init
           pacman -Syu --noconfirm
           pacman -S --noconfirm python python-pip gcc git zlib openssl