Fix Pylint issue

Assigning result of a function call, where the function has no return

Author: DimitriPapadopoulos

tests/ndarray/test_lazyexpr.py

@@ -1397,7 +1397,7 @@ def test_missing_operator():
     a = blosc2.arange(10, urlpath="a.b2nd", mode="w")
     b = blosc2.arange(10, urlpath="b.b2nd", mode="w")
     expr = blosc2.lazyexpr("a + b")
-    c = expr.save("expr.b2nd", mode="w")
+    expr.save("expr.b2nd", mode="w")
     # Remove the file for operand b
     blosc2.remove_urlpath("b.b2nd")
     # Re-open the lazy expression