stack/slapos: version up slapos.rebootstrap 3.10 to prevent build loop when...

stack/slapos: version up slapos.rebootstrap 3.10 to prevent build loop when zc.buildout version changes.

stack/slapos.cfg

@@ -139,7 +139,7 @@ slapos.cookbook = 1.0.48
 slapos.core = 1.3.18
 slapos.extension.strip = 0.2
 slapos.libnetworkcache = 0.14.5
-slapos.rebootstrap = 3.8
+slapos.rebootstrap = 3.10
 slapos.recipe.build = 0.32
 slapos.recipe.cmmi = 0.4
 stevedore = 1.21.0