Fixed docker tests.

src/ssh_audit/__main__.py

@@ -1,2 +1,16 @@
+import sys
+import traceback
+
 from ssh_audit.ssh_audit import main
-main()
+from ssh_audit import exitcodes
+
+
+exit_code = exitcodes.GOOD
+
+try:
+    exit_code = main()
+except Exception:
+    exit_code = exitcodes.UNKNOWN_ERROR
+    print(traceback.format_exc())
+
+sys.exit(exit_code)