nixosTests.nginx*: nginxUnstable -> nginxMainline

Stop using the old `nginxUnstable` alias, which is invalid in tests
since 3edde6562e.

nixos/tests/nginx-variants.nix

@@ -29,5 +29,5 @@ builtins.listToAttrs (
         };
       }
     )
-    [ "nginxStable" "nginxUnstable" "nginxShibboleth" "openresty" "tengine" ]
+    [ "nginxStable" "nginxMainline" "nginxShibboleth" "openresty" "tengine" ]
 )

nixos/tests/nginx.nix

@@ -56,11 +56,11 @@ import ./make-test-python.nix ({ pkgs, ... }: {
       };
 
       specialisation.reloadRestartSystem.configuration = {
-        services.nginx.package = pkgs.nginxUnstable;
+        services.nginx.package = pkgs.nginxMainline;
       };
 
       specialisation.reloadWithErrorsSystem.configuration = {
-        services.nginx.package = pkgs.nginxUnstable;
+        services.nginx.package = pkgs.nginxMainline;
         services.nginx.virtualHosts."!@$$(#*%".locations."~@#*$*!)".proxyPass = ";;;";
       };
     };