tests: Fix test_compose.sh paths

The paths need to be absolute so that subprocesses started during the
compose with a modified cwd will still work.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_compose.sh

@@ -2,7 +2,7 @@
 
 set -e
 
-HERE=$(dirname "$0")
+HERE=$(realpath "$(dirname "$0")")
 
 PYTHONPATH=$HERE/../:$PYTHONPATH
 PATH=$HERE/../bin:$PATH