nixos/mailman: remove spurious uwsgi.service dep

b478e0043c removed every other instance of uwsgi.service and
httpd.service from Mailman before and requiredBy lists.  This one
looks like it was just missed, since I can't see a reason to keep it
but remove the others.

Fixes: b478e0043c ("nixos/mailman: refactor")

nixos/modules/services/mail/mailman.nix

@@ -367,7 +367,7 @@ in {
 
       mailman-web-setup = {
         description = "Prepare mailman-web files and database";
-        before = [ "uwsgi.service" "mailman-uwsgi.service" ];
+        before = [ "mailman-uwsgi.service" ];
         requiredBy = [ "mailman-uwsgi.service" ];
         restartTriggers = [ config.environment.etc."mailman3/settings.py".source ];
         script = ''