hdl.ast: remove Shape<>tuple comparisons.

See #691.

I missed this in commit 29502442.

amaranth/hdl/ast.py

@@ -116,15 +116,6 @@ class Shape:
             return "unsigned({})".format(self.width)
 
     def __eq__(self, other):
-        # TODO(nmigen-0.4): remove
-        if isinstance(other, tuple) and len(other) == 2:
-            width, signed = other
-            if isinstance(width, int) and isinstance(signed, bool):
-                return self.width == width and self.signed == signed
-            else:
-                raise TypeError("Shapes may be compared with other Shapes and (int, bool) tuples, "
-                        "not {!r}"
-                        .format(other))
         if not isinstance(other, Shape):
             try:
                 other = self.__class__.cast(other)