Update python_gtk to debian stretch

When I upgraded Python earlier, I missed the python_gtk repo.

Change-Id: Ie10be829730513d630306d779dc329f4417cdd7f
diff --git a/debian/BUILD b/debian/BUILD
index 11f9349..ec2020b 100644
--- a/debian/BUILD
+++ b/debian/BUILD
@@ -216,6 +216,9 @@
         "libz-dev",
         "python3-dev",
         "python3",
+        "libblas.so.3",
+        "liblapack.so.3",
+        "libstdc++-dev",
     ],
     packages = [
         "libgtk-3-dev",