.gitlab-ci.yml: add missing python-gobject test

Commit 600132f8c08a5ae3d399559dd9c17d3b7b4c6ae3 added a test for
python-gobject but failed to update .gitlab-ci.yml. Do that now.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

.gitlab-ci.yml

@@ -449,6 +449,7 @@ tests.package.test_python_crossbar.TestPythonPy3Crossbar: { extends: .runtime_te
 tests.package.test_python_cryptography.TestPythonPy2Cryptography: { extends: .runtime_test }
 tests.package.test_python_cryptography.TestPythonPy3Cryptography: { extends: .runtime_test }
 tests.package.test_python_django.TestPythonPy3Django: { extends: .runtime_test }
+tests.package.test_python_gobject.TestPythonPy2Gobject: { extends: .runtime_test }
 tests.package.test_python_incremental.TestPythonPy2Incremental: { extends: .runtime_test }
 tests.package.test_python_incremental.TestPythonPy3Incremental: { extends: .runtime_test }
 tests.package.test_python_passlib.TestPythonPy2Passlib: { extends: .runtime_test }