Update just released tutorial's date

Author: petrasovaa

content/tutorials/hydro_flattening/hydro_flatenning.qmd

@@ -1,7 +1,7 @@
 ---
 title: "Hydro-flattening a Digital Elevation Model"
 author: "Doug Newcomb & Anna Petrasova"
-date: 2025-06-17
+date: 2025-09-15
 date-modified: today
 lightbox: true
 image: thumbnail.webp