build: missing deb pkg on ubuntu-20.04

- The vpp build on the ubuntu-20.04 executor failed
  due to the package 'dh-python' not getting
  installed by 'make install-dep'

Type: fix

Signed-off-by: Dave Wallace <dwallacelf@gmail.com>
Change-Id: Id9307ad1b4e34c413d90258c6bde2aa5afafec63
diff --git a/Makefile b/Makefile
index cf4cfad..8fd0b91 100644
--- a/Makefile
+++ b/Makefile
@@ -62,7 +62,7 @@
 # +libganglia1-dev if building the gmond plugin
 
 DEB_DEPENDS  = curl build-essential autoconf automake ccache
-DEB_DEPENDS += debhelper dkms git libtool libapr1-dev dh-systemd
+DEB_DEPENDS += debhelper dkms git libtool libapr1-dev dh-systemd dh-python
 DEB_DEPENDS += libconfuse-dev git-review exuberant-ctags cscope pkg-config
 DEB_DEPENDS += lcov chrpath autoconf indent clang-format libnuma-dev
 DEB_DEPENDS += python3-all python3-setuptools check