hacking: suppress prompt while installing ubuntu deps

Author: Mohit-Chachada

HACKING.md

@@ -49,7 +49,7 @@ Build dependencies can automatically be resolved using `build-dep` on Ubuntu:
 
     cd ~/snapd
     ln -sfn packaging/ubuntu-16.04 debian
-    sudo apt build-dep .
+    sudo apt build-dep -y .
 
 > [!NOTE]
 > The `debian` symbolic link is intentionally not part of the tree, and is explicitly listed in the .gitignore file.