Dataset size has the wrong units when importing

[gavin-k-lee]

Describe the bug
When running renku dataset import a-renku-dataset, the size of a particular dataset is incorrectly rendered (units of data size).

To Reproduce
Steps to reproduce the behavior:

1. Start a renku session with renku --version >=1.0.2
2. Import an existing Renku dataset, for example, run renku dataset import https://renkulab.io/datasets/7de56489-ea49-496c-a95c-fa873e22a133 or renku dataset import https://renkulab.io/datasets/034e8d66-03df-4a6f-a472-2c0246b5edd8.
3. See that the size of the dataset is not quoted properly - it displays bytes instead of MB as in the header.

Expected behavior
The dataset size should correspond to the units that are quoted in the header.

Screenshots and/or execution output

(py39) gavin@gavin-XPS-13-9310:~/Repositories/my-cli-project$ renku dataset import https://renkulab.io/datasets/7de56489-ea49-496c-a95c-fa873e22a133
Successfully applied 1 migrations.e5dc552263a6a15659adf5c904b1d
CHECKSUM                                  NAME         SIZE (MB)  TYPE
----------------------------------------  ---------  -----------  ------
7e89bc5b601f784892f34cb4cba0a8a05ec1badd  wine.data     10969.00  data
Warning: Do you wish to download this version? [y/N]: y
OK                                                                             
(py39) gavin@gavin-XPS-13-9310:~/Repositories/my-cli-project$ renku dataset import https://renkulab.io/datasets/034e8d66-03df-4a6f-a472-2c0246b5edd8
Successfully applied 1 migrations.0dd3c224c5b83deb7d3732138feb6
CHECKSUM                                  NAME                                  SIZE (MB)  TYPE
----------------------------------------  ----------------------------------  -----------  ------
09515fa5f679f8addee1ed52e910528f4963a912  healthcare-dataset-stroke-data.csv    317000.00  csv
Warning: Do you wish to download this version? [y/N]: y
Info: Adding these files to Git LFS:
	data/stroke-patients/healthcare-dataset-stroke-data.csv
To disable this message in the future, run:
	renku config set show_lfs_message False
OK                                                                             
(py39) gavin@gavin-XPS-13-9310:~/Repositories/my-cli-project$ renku --version
1.0.2

Run environment (please complete the following information):

• renku-python version == 1.0.2
• Python version == 3.9
• local terminal OR renkulab interactive environment? == local