Can't specify single color for `render_label` by a color string

[ziyuanzhao2000]

Please see the simple MWE:

import spatialdata as sd
from spatialdata.models import Labels2DModel
sdata_test = sd.SpatialData()
labels = np.ones((10, 10), dtype=np.uint8)
sdata_test['labels'] = Labels2DModel.parse(labels)
sdata_test.pl.render_labels('labels', color='green').pl.show()

However, I cannot specify the label mask to be rendered in green...

This is what I get

[timtreis]

We're currently working on homogenising the color handling in #497, but in the meantime you can just substitute color for na_color and it'll work