haskellPackages.http-link-header: disable tests

The test

  Network.HTTP.Link, writeLinkHeader → parseLinkHeader, roundtrips successfully

seems to flap, as I cannot reproduce the failure locally, but it occured on
Hydra [0]. Also upstream is aware of the problem [1].

[0] https://hydra.nixos.org/build/75041105
[1] https://github.com/myfreeweb/http-link-header/issues/7