Added a new conference, move one from current to past, changed Status of ATD

[boris779]

Pull Request Template: Add a Conference or Workshop

-) Added International Quality Days in Vienna
-) moved one from current to past
-) changed Status of ATD 2026 because CFP is already closed

Conference/Workshop Details

• [ X] Name, Location, Date(s), Website URL and Status are required
• [ X] X / Twitter is Optional
• [ X] Location should be City + Country or Online
• [ X] Status can include information about registration, pricing, calls for proposals and can include links to all the above.

Checklist

• [ X] I have added the conference/workshop to the correct YAML file (_data/current.yml or _data/past.yml)
• [ X] The entry includes name, location, date(s), url and accurate status
• [ X] The entry is in chronological order (soonest to furtherest away)
• [ X] If there are any special characters in the name field (: or ; or '), the name must be in quotes (")
• [ X] I have checked for duplicates to avoid listing the same event twice
• [ X] Build runs successfully