nixosTests.dnscrypt-proxy2: Check that a UDP port is being listened on
nixosTests.dnscrypt-proxy2: Check that a UDP port is being listened on

Motivation: Ensure this test catches startup failures such as
https://github.com/NixOS/nixpkgs/issues/197443

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs