fix "/etc/apt/sources.list: No such file or directory" error

correct sed params

php-fpm/Dockerfile

@@ -28,7 +28,7 @@ ENV DEBIAN_FRONTEND noninteractive
 ARG CHANGE_SOURCE=false
 RUN if [ ${CHANGE_SOURCE} = true ]; then \
     # Change application source from deb.debian.org to tsinghua source
-    sed -i 's/deb.debian.org/mirrors.tuna.tsinghua.edu.cn/g' /etc/apt/sources.list.d/debian.sources \
+    sed -i 's#deb.debian.org/debian$#mirrors.tuna.tsinghua.edu.cn/debian#' /etc/apt/sources.list.d/debian.sources \
 ;fi
 
 # always run apt update when start and after add new source list, then clean up at end.