Update _downloads/2024-09-04-2.12.20.md

Co-authored-by: Philippus Baalman <philippus@gmail.com>

Author: SethTisue

_downloads/2024-09-04-2.12.20.md

@@ -1,6 +1,6 @@
 ---
 title: Scala 2.12.20
-start: 2 September 2024
+start: 4 September 2024
 layout: downloadpage
 release_version: 2.12.20
 release_date: "September 2, 2024"