CI: add missing API stub-implementation for pylint

ci/libcalamares/job.py

+#   SPDX-FileCopyrightText: no
+#   SPDX-License-Identifier: CC0-1.0
+#
+# Stubs for part of the Python API from libcalamares
+# (although the **actual** API is presented through
+# Boost::Python, not as a bare C-extension) so that
+# pylint doesn't complain about libcalamares internals.
+
+configuration = dict()
+
+def setprogress(_): pass
+
+def pretty_name(): return ""
+
+def working_path(): return ""