Fix windows builds for python 3.10

[antonymilne]

Windows, Python 3.10 builds seem to be broken. Investigating this in #1374. At the moment, pip compile and e2e tests seem to work ok and it's just the unit tests that are broken. The error we're getting is:

Importing fiona resulted in: DLL load failed while importing ogrext: The specified procedure could not be found.

And these are the failing tests:

FAILED tests/extras/datasets/geojson/test_geojson_dataset.py::TestGeoJSONDataSet::test_save_and_load[None-save_args0-None]
FAILED tests/extras/datasets/geojson/test_geojson_dataset.py::TestGeoJSONDataSet::test_exists[None-save_args0-None]
FAILED tests/extras/datasets/geojson/test_geojson_dataset.py::TestGeoJSONDataSetVersioned::test_save_and_load[None-None]
FAILED tests/extras/datasets/geojson/test_geojson_dataset.py::TestGeoJSONDataSetVersioned::test_exists[None-None]
FAILED tests/extras/datasets/geojson/test_geojson_dataset.py::TestGeoJSONDataSetVersioned::test_prevent_override[None-None]
FAILED tests/extras/datasets/geojson/test_geojson_dataset.py::TestGeoJSONDataSetVersioned::test_save_version_warning[2019-01-02T00.00.00.000Z-2019-01-01T23.59.59.999Z]
FAILED tests/extras/datasets/geojson/test_geojson_dataset.py::TestGeoJSONDataSetVersioned::test_versioning_existing_dataset[None-save_args0-None-None-None

[antonymilne]

Looking at the last time the job succeeded on develop, the only obvious change is this:

-fiona-1.8.21               |  py310he438f8f_0         885 KB  conda-forge
+fiona-1.8.21               |  py310he438f8f_1         866 KB  conda-forge
-gdal-3.4.2                 |  py310h2a306c7_1         1.7 MB  conda-forge
+gdal-3.4.2                 |  py310h2a306c7_2         1.6 MB  conda-forge
-libgdal-3.4.2              |       he73c9d4_1         9.8 MB  conda-forge
+libgdal-3.4.2              |       hf817787_2         9.7 MB  conda-forge

I suspect that the problem was caused by the new fiona build (_1 vs _0). This was done in conda-forge/fiona-feedstock#191, and it seems that other people have reported problems with importing on Windows as a result.

So I think this will probably fix itself when fiona release a new build. If that doesn't happen for a while, we can skip those unit tests on Windows, Python 3.10 or try to install the old build of fiona. For now I think we should just ignore the fails.