test_manifold: Force eigen_solver="dense"

Avoid an "ARPACK error 3: No shifts could be applied ..." when running
tests on Windows.

Author: ales-erjavec

Orange/tests/test_manifold.py

@@ -56,7 +56,8 @@ def __lle_test_helper(self, data, n_com):
         lle = lle(data)
 
         ltsa = LocallyLinearEmbedding(n_neighbors=5, n_components=n_com,
-                                      method="ltsa")
+                                      method="ltsa",
+                                      eigen_solver="dense")
         ltsa = ltsa(data)
 
         hessian = LocallyLinearEmbedding(n_neighbors=15, n_components=n_com,