nix.nixos-configurations.dev-server: ipv4 static route for bridge103

Unlike the hypervisors during the show: The dev-server has multiple
networks that its apart of: HE Tunnel + Scale Expo Network. Thus we must
be explicit about which route the entire 10.0.0.0/8 should take.

Co-authored-by: Owen DeLong <owen@delong.com>

nix/nixos-configurations/dev-server/default.nix

@@ -391,6 +391,13 @@
                 "10.0.3.20/24"
                 "2001:470:f026:103::20/64"
               ];
+              routes = [
+                {
+                  routeConfig.Destination = "10.0.0.0/8";
+                  routeConfig.Gateway = "10.0.3.1";
+                  routeConfig.GatewayOnLink = true;
+                }
+              ];
             };
             "50-bridge104" = {
               matchConfig.Name = "bridge104";