gss: drop a crashing test

https://hydra.nixos.org/build/266280498/nixlog/1/tail

In the test sources I see lines hinting at the moment it started failing
  name:endtime  type:GENERALIZED_TIME  value:20240711155558Z
but I was unable to find a fix quickly.

(cherry picked from commit f6f5b1f)

pkgs/development/libraries/gss/default.nix

@@ -13,6 +13,10 @@ stdenv.mkDerivation rec {
     url = "mirror://gnu/gss/gss-${version}.tar.gz";
     hash = "sha256-7M6r3vTK4/znIYsuy4PrQifbpEtTthuMKy6IrgJBnHM=";
   };
+  # This test crashes now.  Most likely triggered by expiration on 20240711.
+  postPatch = ''
+    rm tests/krb5context.c
+  '';
 
   buildInputs = lib.optional withShishi shishi;