Normalized array is overwritten when after creating GaussianTissueMask with downsampling_factor = 1

[pablo-mas]

When trying to create a GaussianTissueMask with downsampling_factor = 1, it overwrites the normalized_array previsouly created (with Macenko or Vahadane normalizer).

The error was reproduced here, with images from SICAPv2 and an other dataset : https://github.com/pablo-mas/seggini_downsampling