chore(grfn/home): Use stable emacs

I don't really need anything from unstable emacs atm, and it's...
unstable.

Change-Id: Ibd30f9f767e374c7e9fc125c494c414fd26815a7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9082
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
Autosubmit: grfn <grfn@gws.fyi>

users/grfn/system/home/modules/emacs.nix

@@ -65,7 +65,7 @@ in
 
       programs.emacs = {
         enable = true;
-        package = pkgs.emacs-unstable;
+        package = pkgs.emacs;
         extraPackages = (epkgs:
           (with epkgs; [
             tvlPackages.dottime