spanner db_api: credentials_uri raise parameter error

[HemangChothani]

Documents settings.py for python-spanner-django

DATABASES = {
 'default': {
 'ENGINE': 'django_spanner',
 'PROJECT': '<GCP_project_id>',
 'INSTANCE': '<instance_id>',
 'NAME': '<database_name>',
 'OPTIONS': {
 'credentials_uri': '<credentials_uri>',
 },
 },
}

TypeError: connect() got an unexpected keyword argument 'credentials_uri'

Reference issue : googleapis/python-spanner-django#582

The paramter credentials_uri was there when db_api is part of python-spanner-django, but it removed or replaced by credentials parameter when it moved to python-spanner.