[Examples]GATNE-T example uses gensim package, which in turn uses deprecated and removed API

## 🐛 Bug

GATNE-T example uses gensim package. That package, in turn, uses scipy.linalg.triu, which was deprecated and removed in latest scipy: https://docs.scipy.org/doc/scipy/release/1.11.0-notes.html#deprecated-features

## To Reproduce

Run the example. Get this:
Traceback (most recent call last):
File "/workspace/examples/GATNE-T/src/main_sparse.py", line 14, in
from utils import *
File "/opt/dgl/dgl-source/examples/pytorch/GATNE-T/src/utils.py", line 10, in
from gensim.models.keyedvectors import Vocab
File "/usr/local/lib/python3.10/dist-packages/gensim/__init__.py", line 11, in
from gensim import parsing, corpora, matutils, interfaces, models, similarities, utils # noqa:F401
File "/usr/local/lib/python3.10/dist-packages/gensim/corpora/__init__.py", line 6, in
from .indexedcorpus import IndexedCorpus # noqa:F401 must appear before the other classes
File "/usr/local/lib/python3.10/dist-packages/gensim/corpora/indexedcorpus.py", line 14, in
from gensim import interfaces, utils
File "/usr/local/lib/python3.10/dist-packages/gensim/interfaces.py", line 19, in
from gensim import utils, matutils
File "/usr/local/lib/python3.10/dist-packages/gensim/matutils.py", line 20, in
from scipy.linalg import get_blas_funcs, triu
ImportError: cannot import name 'triu' from 'scipy.linalg' (/usr/local/lib/python3.10/dist-packages/scipy/linalg/__init__.py)

## Expected behavior

No import errors

## Environment

It was discovered in Nvidia DGL container, but I see that here gensim is still used.