message: Add finite timeout on CURL metrics endpoint.
  Prevent CURL hanging up without timeout when connection can't be established. Creating a deadlock on the filesystem when executed behind a proxy.
diff: @@ -483,6 +483,8 @@ namespace vcpkg::Metrics
  // TODO: convert to cmd_execute_background or something.
  auto curl = System::Command("curl")
  .string_arg("https://dc.services.visualstudio.com/v2/track")
  + .string_arg("--max-time")
  + .string_arg("3")
  .string_arg("-H")
  .string_arg("Content-Type: application/json")
  .string_arg("-X")
  