stack/slapos: version ↑ slapos.libnetworkcache 0.16

( not needed for the current work on jsonschema draft 7 support, but
done at the same time, to merge together two unrelated changes which
cause recompilation so that we recompile only once )

stack/slapos.cfg

@@ -138,7 +138,7 @@ slapos.cookbook = 1.0.75
 slapos.core = 1.4.11
 slapos.extension.strip = 0.4
 slapos.extension.shared = 1.0
-slapos.libnetworkcache = 0.15
+slapos.libnetworkcache = 0.16
 slapos.rebootstrap = 4.1
 slapos.recipe.build = 0.39
 slapos.recipe.cmmi = 0.8