small bugfixes and updates

py_wake/deficit_models/__init__.py

py_wake/deficit_models/deficit_model.py

py_wake/deficit_models/gcl.py

py_wake/rotor_avg_models/rotor_avg_model.py

py_wake/site/_site.py

py_wake/tests/check_speed.py

py_wake/tests/test_deficit_models/test_deficit_models.py

py_wake/tests/test_deficit_models/test_gcl.py

py_wake/tests/test_sites/test_site.py

py_wake/tests/test_sites/test_wasp_grid_site.py

py_wake/tests/test_sites/test_xrsite.py

py_wake/tests/test_utils/test_grid_interpolator.py

.../test_wind_farm_models/test_enginering_wind_farm_model.py

py_wake/tests/test_wind_farm_models/test_parallel_aep.py

py_wake/utils/progressbar.py

py_wake/wind_farm_models/wind_farm_model.py