feat(modules/base.nix): add more cache mirrors

Author: ryan4yin

modules/base.nix

@@ -92,9 +92,10 @@
     substituters = [
       # cache mirror located in China
       # status: https://mirror.sjtu.edu.cn/
-      # "https://mirror.sjtu.edu.cn/nix-channels/store"
+      "https://mirror.sjtu.edu.cn/nix-channels/store"
       # status: https://mirrors.ustc.edu.cn/status/
       "https://mirrors.ustc.edu.cn/nix-channels/store"
+      "https://mirrors.tuna.tsinghua.edu.cn/nix-channels/store"
 
       "https://nix-community.cachix.org"
       # my own cache server