UnicodeEncodeError when editing a text file

UnicodeEncodeError occurs when updating a data product with text that includes unicode characters: https://github.com/apache/airavata-django-portal/blob/develop/django_airavata/apps/api/views.py#L826-L829

Steps to reproduce

1. Upload a text file into user storage
2. Click on the file.
3. In the editor, add the following characters to the file.

ización aci

4. Save file

Expected results

File saves successfully

Actual results

Error message 'ascii' codec can't encode character '
xf3' in position 5: ordinal not in range(128) and file fails to save.