Use ghcr.io/loong64/alpine:edge for loong64 Docker build

Author: nekohasekai

.github/workflows/docker.yml

@@ -170,7 +170,7 @@ jobs:
           - { platform: "linux/ppc64le" }
           - { platform: "linux/riscv64" }
           - { platform: "linux/s390x" }
-          - { platform: "linux/loong64", base_image: "debian:stable-slim" }
+          - { platform: "linux/loong64", base_image: "ghcr.io/loong64/alpine:edge" }
     steps:
       - name: Get commit to build
         id: ref