Run Python 3 CI job with minimal configuration

This helps to detect issues when building with disabled modules.

.gitlab-ci.yml

@@ -27,6 +27,7 @@
 gcc:python3:
   extends: .test
   variables:
+    CONFIG: "--without-crypto --without-debug --without-debugger --without-plugins"
     CFLAGS: "-O2"
     PYTHON: "/usr/bin/python3"