tests: fix lint error in tests

[MatteoVoges]

There was a lint error in the tests:

tests/test_basic_ops_dict.py:276: error: Keywords must be strings  [misc]
Installing missing stub packages:
/home/circleci/project/.nox/lint-3-10/bin/python -m pip install types-Pygments types-colorama types-setuptools

Found 1 error in 1 file (checked 81 source files)

The problem is, that mypy detects the dict unpacking operator ** in the function call as syntax error. So I adjusted the test, that the unpacking is still tested, but it don't happen in the function call anymore.

This is by the way a common requested feature / bugfix in mypy. References:

• https://stackoverflow.com/questions/47632128/how-to-get-mypy-to-accept-an-unpacked-dict
• https://github.com/python/mypy/issues/5869
• https://github.com/python/mypy/issues/10023