Bump upstream V8 version

ignisf · ignisf · commit 05c391458fdc · 2018-11-16T11:53:04.000+02:00
diff --git a/lib/libv8/version.rb b/lib/libv8/version.rb
@@ -1,3 +1,3 @@
 module Libv8
-  VERSION = "6.8.275.24.0beta1"
+  VERSION = "7.0.276.38.0beta1"
 end
diff --git a/vendor/depot_tools b/vendor/depot_tools
@@ -1 +1 @@
-Subproject commit 120b2e4f2660a4c583996d5334cff1fc65c251f0
+Subproject commit 8ada4d523eb440c9978390a8a38fe167b576b91e
