__neg__ (unary -) for array (#1107)

Author: Alexander-Makaryev

dpnp/dpnp_array.py

@@ -208,7 +208,9 @@ def __mul__(self, other):
     def __ne__(self, other):
         return dpnp.not_equal(self, other)
 
- # '__neg__',
+    def __neg__(self):
+        return dpnp.negative(self)
+
  # '__new__',
  # '__or__',
  # '__pos__',