ot.gpu.da.sinkhorn_lpl1: TypeError: Expected list, got tuple

Describe the bug

ot.gpu.da.sinkhorn_lpl1 crashes with error "TypeError: Expected list, got tuple"

To Reproduce

Run test_gpu_sinkhorn_lpl1() in file https://github.com/PythonOT/POT/blob/master/test/test_gpu.py

Output:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
/tmp/ipykernel_162490/3474066936.py in <module>
----> 1 test_gpu_sinkhorn_lpl1()

/tmp/ipykernel_162490/3323216572.py in test_gpu_sinkhorn_lpl1()
     18 
     19         G = ot.da.sinkhorn_lpl1_mm(wa, labels_a, wb, M, reg)
---> 20         G1 = ot.gpu.da.sinkhorn_lpl1_mm(wa, labels_a, wb, M, reg)
     21 
     22         np.testing.assert_allclose(G1, G, rtol=1e-10)

~/.cache/pypoetry/virtualenvs/venvproject-py3.7/lib/python3.7/site-packages/ot/gpu/da.py in sinkhorn_lpl1_mm(a, labels_a, b, M, reg, eta, numItermax, numInnerItermax, stopInnerThr, verbose, log, to_numpy)
    121     classes = npp.unique(labels_a2)
    122     for c in classes:
--> 123         idxc, = utils.to_gpu(npp.where(labels_a2 == c))
    124         indices_labels.append(idxc)
    125 

~/.cache/pypoetry/virtualenvs/venvproject-py3.7/lib/python3.7/site-packages/ot/gpu/utils.py in to_gpu(*args)
     91         return (cp.asarray(x) for x in args)
     92     else:
---> 93         return cp.asarray(args[0])
     94 
     95 

~/.cache/pypoetry/virtualenvs/venvproject-py3.7/lib/python3.7/site-packages/cupy/_creation/from_data.py in asarray(a, dtype, order)
     64 
     65     """
---> 66     return _core.array(a, dtype, False, order)
     67 
     68 

cupy/_core/core.pyx in cupy._core.core.array()

cupy/_core/core.pyx in cupy._core.core.array()

TypeError: Expected list, got tuple

Environment (please complete the following information):

OS (e.g. MacOS, Windows, Linux): Ubuntu 20.10
Python version: 3.7.12
How was POT installed (source, pip, conda): poetry (uses pip)
Build command you used (if compiling from source):
Only for GPU related bugs:
- CUDA version: 11.1
- GPU models and configuration: Nvidia RTX 3090
- Any other relevant information: POT 0.7.0, Cupy 9.4.0 (cupy-111)

Output of the following code snippet:

import platform; print(platform.platform())
import sys; print("Python", sys.version)
import numpy; print("NumPy", numpy.__version__)
import scipy; print("SciPy", scipy.__version__)
import ot; print("POT", ot.__version__)

Linux-5.8.0-63-generic-x86_64-with-debian-bullseye-sid
Python 3.7.12 (default, Sep 15 2021, 10:55:12)
[GCC 10.3.0]
NumPy 1.21.1
SciPy 1.6.1
POT 0.7.0