adapt config for normalization layer in rnn

[AnFreTh]

This pull request introduces a change to the initialization process of the TabulaRNN class in the tabularnn.py file. The most important changes involve the reordering of the initialization of the normalization layer and the introduction of the replace function from the dataclasses module.

Initialization process improvements:

• Added import for the replace function from the dataclasses module. (mambular/base_models/tabularnn.py)
• Moved the initialization of the normalization layer to use a temporary configuration object created with the replace function. (mambular/base_models/tabularnn.py)