bpo-39969: Remove ast.Param node class as is no longer used (GH-19020)

diff --git a/Include/Python-ast.h b/Include/Python-ast.h
index f4631f2..c44d6ea 100644
--- a/Include/Python-ast.h
+++ b/Include/Python-ast.h
@@ -17,8 +17,8 @@
 
 typedef struct _expr *expr_ty;
 
-typedef enum _expr_context { Load=1, Store=2, Del=3, AugLoad=4, AugStore=5,
-                             Param=6 } expr_context_ty;
+typedef enum _expr_context { Load=1, Store=2, Del=3, AugLoad=4, AugStore=5 }
+                             expr_context_ty;
 
 typedef enum _boolop { And=1, Or=2 } boolop_ty;