travis: fix test environment installation

The CLIPS source zip seems corrupted.

Fetch CLIPS package from Debian Unstable.

Signed-off-by: Matteo Cafasso <noxdafox@gmail.com>

.travis_install.sh

@@ -1,26 +1,9 @@
 #!/bin/bash
 
-WORK_DIR=$(pwd)
-CLIPS_DIR=$WORK_DIR/clips_core_source_630
-DOWNLOAD_URL="https://downloads.sourceforge.net/project/clipsrules/CLIPS/6.30/clips_core_source_630.zip"
+echo "deb http://ftp.se.debian.org/debian/ sid main" >> /etc/apt/sources.list
 
-wget -O clips.zip $DOWNLOAD_URL
-
-unzip clips.zip
-
-cd $CLIPS_DIR
-
-cp makefiles/makefile.lib core/Makefile
-
-cd $CLIPS_DIR/core/
-
-sed -i 's/gcc -c/gcc -fPIC -c/g' Makefile
-
-make
-
-ld -G *.o -o libclips.so
-
-cd $WORK_DIR
+sudo apt update
+sudo apt install -t sid libclips libclips-dev
 
 sudo pip install --upgrade pip
 sudo pip install --upgrade setuptools