CI: add missing debian dependencies

debian/control

@@ -1,7 +1,11 @@
 Source: open62541
 Priority: optional
 Maintainer: open62541 Team <open62541-core@googlegroups.com>
-Build-Depends: debhelper (>= 7)
+Build-Depends: debhelper (>= 7.0.50~),
+ cmake (>= 3.0),
+ graphviz,
+ python (>= 2.7),
+ python-six
 Standards-Version: 4.1.2
 Section: libs
 Homepage: https://open62541.org/