microvm: don't mutate users in microvms

modules/microvm.nix

@@ -175,10 +175,13 @@ in
       '';
     };
 
-    # store root users files persistent, especially .bash_history
-    users.users."root" = {
-      createHome = true;
-      home = lib.mkForce "/home/root";
+    users = {
+      mutableUsers = false;
+      # store root users files persistent, especially .bash_history
+      users."root" = {
+        createHome = true;
+        home = lib.mkForce "/home/root";
+      };
     };
   };
 }