Remove SciPy check from aesara.sparse

aesara/sparse/__init__.py

-from warnings import warn
-
-
-try:
-    import scipy
-
-    enable_sparse = True
-except ImportError:
-    enable_sparse = False
-    warn("SciPy can't be imported.  Sparse matrix support is disabled.")
-
+from aesara.sparse import rewriting, sharedvar
+from aesara.sparse.basic import *
+from aesara.sparse.sharedvar import sparse_constructor as shared
 from aesara.sparse.type import SparseTensorType, _is_sparse
 
 
-if enable_sparse:
-    from aesara.sparse import rewriting, sharedvar
-    from aesara.sparse.basic import *
-    from aesara.sparse.sharedvar import sparse_constructor as shared
-
-    def sparse_grad(var):
+def sparse_grad(var):
     """This function return a new variable whose gradient will be
     stored in a sparse format instead of dense.