Update art.json, change contact

[ArtracID]

DID Method Registration

As a DID method registrant, I have ensured that my DID method registration complies with the following statements:

• The DID Method specification defines the DID Method Syntax.
• The DID Method specification defines the Create, Read, Update, and Deactivate DID Method Operations.
• The DID Method specification contains a Security Considerations section.
• The DID Method specification contains a Privacy Considerations section.
• The JSON file I am submitting has passed all automated validation tests below.
• The JSON file contains a contactEmail address [OPTIONAL].
• The JSON file contains a verifiableDataRegistry entry [OPTIONAL].

This is an contact details changes

[msporny]

Approved -- the individual that raised the PR for the art.json entry (@ArtracID) is the one that created it. This is a change of contact information and thus doesn't need further review. Merging.