travis: Install only python3 packages

Change-Id: I3548fa7340afc63557cc65a7a396ecf96c607806
diff --git a/tests/dockerfiles/Kali.docker b/tests/dockerfiles/Kali.docker
index b4a9719..f386049 100644
--- a/tests/dockerfiles/Kali.docker
+++ b/tests/dockerfiles/Kali.docker
@@ -7,13 +7,12 @@
     libtool \
     pkg-config \
     build-essential \
-    python-docutils \
     libcppunit-dev \
     swig \
     doxygen \
     liblog4cpp5-dev \
-    python-gtk2 \
-    python-scipy \
+    python3-docutils \
+    python3-scipy \
     gnuradio-dev gnuradio libgmp-dev libboost-regex-dev \
     libosmocore-dev