from keras.layers.merge import concatenate as concat in dissect_expr causes dissect second model to fail

[SergejRuff]

Hi,

I previosly submitted code and had previous issues I found.
While benchmarking the vae that estimates cell type specific expression, I found a new error.

I am using the up-to-date version of keras, which is the new default.
Keras3 changed their layer module from merge to merging. There you find the code for concatenate
https://github.com/keras-team/keras/tree/master/keras/src/layers/merging

The new names in keras3 causes an error in dissect because you are importing

from keras.layers.merge import concatenate as concat

That causes the error

dissect_expr.py", line 26, in <module>
    from keras.layers.merge import concatenate as concat
ModuleNotFoundError: No module named 'keras.layers.merge'

The proportion estimation works but the second model doesnt work. I will change code and test whether it works and will
submit a pull request that supports the new keras API later.

Best regards,
Sergej Ruff4