[tests] Make bin/saver executable.

tests/autodetect.t

@@ -4,7 +4,7 @@ Test autodetect
   > echo "2.4.0"
   > EOF
 
-  $ chmod u+x bin/alt-ergo bin/pyrat.py bin/Marabou
+  $ chmod u+x bin/alt-ergo bin/pyrat.py bin/Marabou bin/saver
 
   $ bin/alt-ergo
   2.4.0