deps: include stress-ng RPM

For testing numad as part of [1]. The thinking is that we'll
bind mount in COSA into the VM and run a container based on the
COSA rootfs that spanws stress-ng.

[1] coreos/fedora-coreos-config#4051

Author: dustymabe

src/deps.txt

@@ -117,3 +117,7 @@ vim-enhanced
 
 # For reading build-args.conf (environment file)
 python3-dotenv
+
+# For testing numad
+# https://github.com/coreos/fedora-coreos-config/pull/4051
+stress-ng