[Fix] Documentation build errors (NeuralEnsemble#677)

* Fixed missed raw-string specification to avoid build errors related to the LaTeX math statement

* Fixed documentation environment file to use Python 3.12

* Removed metadata to hide cells with plot function declaration in UE tutorial

* Replaced plot function defined in UE tutorial by Viziphant import

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Co-authored-by: Cristiano Köhler <[email protected]>

Author: kohlerca