CI: fix cuda image breakage

From the Zen of Python: "Explicit is better than implicit."

As it turns out, it's no longer a safe assumption that pip uses
setuptools??? Well, anyway, install it properly regardless.

ci/ciimage/cuda/install.sh

@@ -5,7 +5,7 @@ set -e
 source /ci/common.sh
 
 pkgs=(
-  python python-pip
+  python python-pip python-setuptools
   ninja gcc gcc-objc git cmake
   cuda zlib pkgconf
 )