[nix] Fixes deprecated function usage.

system/features/web-containers.nix

@@ -79,7 +79,7 @@
           }:
           let
             fqn = "${hostname}.${domain}";
-            serviceName = lib.strings.replaceChars [ "." ] [ "-" ] fqn;
+            serviceName = builtins.replaceStrings [ "." ] [ "-" ] fqn;
             routerRule = if public then hostRule hostname domain else localHostRule hostname domain;
             homepageLabels =
               if homepageOpts == { } then
@@ -109,8 +109,7 @@
               extraOptions
               ;
             autoStart = true;
-            labels =
-              {
+            labels = {
               "traefik.enable" = "true";
               "traefik.http.routers.${serviceName}.rule" = "${routerRule}";
               "traefik.http.routers.${serviceName}.service" = "${serviceName}";