[future] converter issues due to pd.NA in networks

[KS-HTK]

Issue

There is currently an issue in lightsim2grid and PowerGridModels, they cannot import a network that contains pandas.NA values

With the introduction of pandera this leads to issues with some networks in the tests.

Currently skipped tests should be enabled once the issue in lightsim2grid is resolved:

• test_contingency.py:test_with_lightsim2grid
• test_contingency.py:test_contingency_timeseries
• test_contingency.py:test_cause_congestion
• test_contingency.py:test_cause_element_index

Currently skipped tests should be enabled once the issue in PowerGridModels is resolved:

• test_runpp_pgm.py:test_minimal_net_pgm

[vogt31337]

@KS-HTK , can you link the actual Issue/PR in ls2g ?

[KS-HTK]

Since this is a future issue and not a current one I have not yet opened an issue with ls2g.

We noticed a similar issue with PowerGridModels today so this will be updated for both ls2g and pgm.