Remove reference to H5I_REFERENCE

[dermesser]

Deprecated in 1.10, removed some time later
(https://support.hdfgroup.org/ftp/HDF5/prev-releases/ReleaseFiles/hdf5-1.10.2-RELEASE.txt).

This currently results in a build error:

File "src/raw/dune", line 10, characters 2-11:
10 |   h5i_stubs
       ^^^^^^^^^
h5i_stubs.c: In function ‘H5I_type_val’:
h5i_stubs.c:27:21: error: ‘H5I_REFERENCE’ undeclared (first use in this function); did you mean ‘H5T_REFERENCE’?
   27 |     case  6: return H5I_REFERENCE;
      |                     ^~~~~~~~~~~~~
      |                     H5T_REFERENCE
h5i_stubs.c:27:21: note: each undeclared identifier is reported only once for each function it appears in
h5i_stubs.c: In function ‘Val_h5i_type’:
h5i_stubs.c:51:10: error: ‘H5I_REFERENCE’ undeclared (first use in this function); did you mean ‘H5T_REFERENCE’?
   51 |     case H5I_REFERENCE   : return Val_int( 6);
      |          ^~~~~~~~~~~~~
      |          H5T_REFERENCE

which vanishes upon application of this patch.