Update changelog.mdx

Author: ryanfoxtyler

dgraph/changelog.mdx

@@ -22,7 +22,7 @@ To learn about the latest releases and other important announcements, watch the
 
 | Release               | First Release Date | End of Life    |
 | --------------------- | ------------------ | -------------- |
-| [v25.0 Preview][]     | TBD                | TBD            |
+| [v25.0 Preview][]     | May 2025                | TBD            |
 | [v24.1][]             | March 2025         | September 2026 |
 | [v24.0][]             | June 2024          | December 2025  |
 | [v23.1][]             | October 2023       | April 2025     |