Remove extraneous ')' in abstract.h (GH-19146)

diff --git a/Include/object.h b/Include/object.h
index 564ba29..6c30809 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -27,7 +27,7 @@
 Types themselves are represented as objects; an object contains a
 pointer to the corresponding type object.  The type itself has a type
 pointer pointing to the object representing the type 'type', which
-contains a pointer to itself!).
+contains a pointer to itself!.
 
 Objects do not float around in memory; once allocated an object keeps
 the same size and address.  Objects that must hold variable-size data