fix pytest on VM

[veenstrajelmer]

Running pytest tests/test_modelbuilder.py::test_cmems_nc_to_ini on the VM now raises the following errors due to curly brackets that are trying to be formatted:

=============================================== short test summary info ===============================================
FAILED tests/test_modelbuilder.py::test_cmems_nc_to_ini[midnight] - KeyError: '45c63495-0000-0000-0000-100000000000'
FAILED tests/test_modelbuilder.py::test_cmems_nc_to_ini[noon] - KeyError: '45c63495-0000-0000-0000-100000000000'
FAILED tests/test_modelbuilder.py::test_cmems_nc_to_ini[monthly] - KeyError: '45c63495-0000-0000-0000-100000000000'
================================================== 3 failed in 1.46s ==================================================

This did not happen before, now probably happens because of some VM setting/update. This is not an issue for users, since the error is not raised when just executing the code in Spyder.