Update medico.md

Author: stevenah

_editions/2025/tasks/medico.md

@@ -90,7 +90,7 @@ More details will follow.
 The program will be updated with the exact dates.
 
 * 14 May 2025: Development Data release
-* 30 June 2025: Development Data release
+* 1 September 2025: Testing Data release
 * 12 September 2025: Runs due and results returned.
 * 26 September 2025: Results returned.
 * 08 October 2025: Working notes paper