AttributeError: 'MultiProgressWidget' object has no attribute 'elapsed_time'

I was getting an error that ipywidgets was not installed when I ran the following code

```
from cropmask.preprocess import PreprocessWorkflow, get_arr_channel_mean, setup_dirs
import time
import dask

param_path = "/home/ryan/work/CropMask_RCNN/cropmask/test_preprocess_config.yaml"
scene_list = [
"/mnt/cropmaskperm/unpacked_landsat_downloads/LT050280322005012001T2-SC20190818204900",
"/mnt/cropmaskperm/unpacked_landsat_downloads/LT050310322005021001T1-SC20190818205059",
"/mnt/cropmaskperm/unpacked_landsat_downloads/LT050290312005031601T1-SC20190818204935",
"/mnt/cropmaskperm/unpacked_landsat_downloads/LT050320312005011601T1-SC20190818205113",
]
labels_path = "/mnt/cropmaskperm/external/nebraska_pivots_projected.geojson"

setup_dirs(param_path)

# this is just to get the train dir path
wflow = PreprocessWorkflow(param_path,
scene_list[0],
labels_path)

results = []
for scene_path in scene_list:

wflow = dask.delayed(PreprocessWorkflow)(param_path, scene_path, labels_path)

band_list = dask.delayed(wflow.yaml_to_band_index)()

product_list = dask.delayed(wflow.get_product_paths)(band_list)

dask.delayed(wflow.load_meta_and_bounds)(product_list)

dask.delayed(wflow.load_single_scene)(product_list)

dask.delayed(wflow.stack_and_save_bands)()

dask.delayed(wflow.negative_buffer_and_small_filter)(-31, 100)

dask.delayed(wflow.grid_images)()

dask.delayed(wflow.remove_from_gridded)()

dask.delayed(wflow.move_chips_to_folder)()

result = dask.delayed(wflow.connected_components)()

results.append(result)

# https://docs.dask.org/en/stable/delayed-best-practices.html
from dask.distributed import Client, progress

client = Client() # use dask.distributed by default

x = dask.compute(*results) # start computation in the background
progress(x) # watch progress
```

so then I installed ipywidgets version 7.5.1 in my conda environment that contains Dask and got this error when running the same code again

```
tornado.application - ERROR - Exception in callback functools.partial(>, exception=AttributeError("'MultiProgressWidget' object has no attribute 'elapsed_time'")>)
Traceback (most recent call last):
File "/data/anaconda/envs/cropmask/lib/python3.7/site-packages/tornado/ioloop.py", line 743, in _run_callback
ret = callback()
File "/data/anaconda/envs/cropmask/lib/python3.7/site-packages/tornado/ioloop.py", line 767, in _discard_future_result
future.result()
File "/data/anaconda/envs/cropmask/lib/python3.7/site-packages/distributed/diagnostics/progressbar.py", line 282, in listen
self._draw_stop(**response)
File "/data/anaconda/envs/cropmask/lib/python3.7/site-packages/distributed/diagnostics/progressbar.py", line 381, in _draw_stop
+ ""
AttributeError: 'MultiProgressWidget' object has no attribute 'elapsed_time'

```

I'm not sure what the issue is here, seems to be some sort of version conflict between packages or other internal issue since I'm not invoking the "elapsed_time" attribute directly.

I'm using jupyterlab version 1.0.9, python 3.7, and dask version 2.3