F fix empty diff

Summary

In the course of https://gitlab.indiscale.com/caosdb/customers/leibniz-zmt/management/-/issues/129, an error in the empty_diff function occurred when comparing entities with different ids.

Focus

apiutils.empty_diff now handles special attributes separately.

Test Environment

Unittest should be sufficient. To reproduce previous behavior for manual testing, install pylib in dev and execute

pytest -vvv unittests/test_apiutils.py::test_empty_diff

with the unit test from this branch.

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