fix(web03/postgresql): Increase the maximum number of connexions

machines/nixos/web03/django-apps/default.nix

@@ -14,6 +14,12 @@
     ./wikiens.nix
   ];
 
+  services.postgresql.settings = {
+    # NOTE: Each concurrent Django request opens a DB connection,
+    # by default, the maximum allowed is 100, which is too small whan a lot of requests come in
+    max_connections = 512;
+  };
+
   services.django-apps = {
     enable = true;