fix fialing test due to fista not initializing datafit

Author: mathurinm

skglm/solvers/fista.py

@@ -51,10 +51,12 @@ def _solve(self, X, y, datafit, penalty, w_init=None, Xw_init=None):
         Xw = Xw_init.copy() if Xw_init is not None else np.zeros(n_samples)
 
         if X_is_sparse:
+            datafit.initialize_sparse(X.data, X.indptr, X.indices, y)
             lipschitz = datafit.get_global_lipschitz_sparse(
                 X.data, X.indptr, X.indices, y
             )
         else:
+            datafit.initialize(X, y)
             lipschitz = datafit.get_global_lipschitz(X, y)
 
         for n_iter in range(self.max_iter):