[metamodel] changed the name of the class.

BayesValidRox/BayesInference/BayesInference.py

BayesValidRox/PostProcessing/PostProcessing.py

BayesValidRox/surrogate_models/surrogate_models.py

...ValidRox/tests/AnalyticalFunction/AnalytFuncValid_Test.py

...idRox/tests/AnalyticalFunction/Test_AnalyticalFunction.py

BayesValidRox/tests/BeamTest/Test_Beam.py