gh-100633 Tutorial: Fix dataclasses import (GH-100638)

import dataclass not dataclasses from dataclasses
(cherry picked from commit 98308dbeb1)

Co-authored-by: Owain Davies <116417456+OTheDev@users.noreply.github.com>

Doc/tutorial/classes.rst

@@ -740,7 +740,7 @@ Sometimes it is useful to have a data type similar to the Pascal "record" or C
 "struct", bundling together a few named data items. The idiomatic approach
 is to use :mod:`dataclasses` for this purpose::
 
-    from dataclasses import dataclasses
+    from dataclasses import dataclass
 
     @dataclass
     class Employee: