Update DP Lib to version 2.0.0

[dibakch]

Description

Update the Google DP Library dependency to the most recent version, which has just been released in version 2.0.0.

Checklist

• [ X] I have followed the Contribution Guidelines and Code of Conduct
• [X ] I have commented my code following the OpenMined Styleguide
• [ X] I have labeled this PR with the relevant Type labels
• [X ] My changes are covered by tests

[dibakch]

Okay, this is not as straight forward as I thought..