[SEBA-449]

Add python3-dev package to provide headers so that pip packages that
need to compile C extensions (in this case, Twisted) can be installed.

Change-Id: I27a2a6a74d195d00a453b00f450c27736c608a37
diff --git a/packer/provision/basebuild.sh b/packer/provision/basebuild.sh
index 9f9d06b..0ebb5e4 100644
--- a/packer/provision/basebuild.sh
+++ b/packer/provision/basebuild.sh
@@ -131,6 +131,7 @@
         python-openssl \
         python-pip \
         python-urllib3 \
+        python3-dev \
         ruby \
         socat \
         ssh \