(CI)(venv) drop python2 support

Author: MatthijsBurgh

scripts/travis/setup-venv.sh

@@ -8,11 +8,7 @@ source $BASEDIR/defaults.sh
 VENV_DIR=${1:-~/venv}
 
 # setup our own virtualenv
-if $WITH_PYTHON3; then
-    PYTHON_EXE='/usr/bin/python3'
-else
-    PYTHON_EXE='/usr/bin/python2'
-fi
+PYTHON_EXE='/usr/bin/python3'
 
 # use --system-site-packages so that Python will use deb packages
 virtualenv $VENV_DIR -p $PYTHON_EXE --system-site-packages