Describe the bug
when I Use The Code Below,I got an error called:"TypeError: must be str, not int" at hdftools.py line 88, in _dicts_to_group
h5file[path + key] = item
To Reproduce
x_dataset = to_time_series_dataset(result_aray)
y_dataset=np.array(total_y)
n_ts, ts_sz = x_dataset.shape[:2]
n_classes=len(set(y_dataset))
shapelet_sizes = grabocka_params_to_shapelet_size_dict(n_ts=n_ts,ts_sz=ts_sz,n_classes=n_classes,l=0.1,r=1)
shp_clf = LearningShapelets(n_shapelets_per_size=shapelet_sizes,optimizer=tf.optimizers.Adam(.01),batch_size=16,weight_regularizer=.01,max_iter=200,random_state=42,verbose=0)
shp_clf.fit(x_dataset, y_dataset)
shp_clf.to_hdf5("timeservice.hdf5")
Expected behavior
any one who have an idea about this problom?
Environment (please complete the following information):

• OS:Windows 10
• tslearn version [0.5.0.5]
  Additional context
  when I try to run the example plot_shapelets.py ,and then call the to_hdf5 method ,I got the same error.