hdf5: move to a more stable URL

pkgs/tools/misc/hdf5/default.nix

···
   version = "1.8.14";
   name = "hdf5-${version}";
   src = fetchurl {
-    url = "http://www.hdfgroup.org/ftp/HDF5/current/src/hdf5-${version}.tar.gz";
+    url = "http://www.hdfgroup.org/ftp/HDF5/releases/hdf5-${version}/src/hdf5-${version}.tar.gz";
     sha256 = "0f86gv32pjrrphvamgims1dd7f3bp46hjarbcdy8k4gmyzpgxghx";
  };