Add release date to CHANGELOG.md

Closes #60127

GitOrigin-RevId: 9dc538d
Change-Id: Idad8f595a26e2ebbaa1857e7cabe616b698af119
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/409741
Reviewed-by: Alexander Thomas <[email protected]>

Author: mateusfccp

CHANGELOG.md

@@ -32,7 +32,7 @@ disallowed.
 
 ## 3.7.0
 
-**Released on:** Unreleased
+**Released on:** 2025-02-12
 
 ### Language