deb: only require build-essential on system-setup

devscripts are convenient to have, but they're big so only require
build-essential package on debian systems instead.

apkg/pkgstyles/deb.py

@@ -44,7 +44,7 @@ SUPPORTED_DISTROS = [
     "raspbian",
 ]
 DISTRO_REQUIRES = {
-    'core': ['devscripts'],
+    'core': ['build-essential'],
     'isolated': ['pbuilder'],
 }