flake.nix: Update inputs and fix nix run command

flake.nix

@@ -13,7 +13,7 @@
     };
 
     tlaternet-templates = {
-      url = "git+https://gitea.tlater.net/tlaternet/tlaternet.git";
+      url = "git+https://gitea.tlater.net/tlaternet/tlaternet-templates.git";
       # No need to override anything here; we can save some downloads
       # if we rely on the webserver to do that.
     };
@@ -57,8 +57,8 @@
     apps.${system} = {
       run-with-templates = let
         script = pkgs.writeShellScriptBin "run-with-templates" ''
-          export ROCKET_TEMPLATE_DIR=${tlaternet-templates.packages.${system}.tlaternet-templates}
-          ${self.packages.${system}.tlaternet-webserver}/bin/tlaternet-webserver
+          RUST_LOG=info ${self.packages.${system}.tlaternet-webserver}/bin/tlaternet-webserver \
+              --template-directory ${tlaternet-templates.packages.${system}.default}
         '';
       in {
         type = "app";