Delete stale ASDL update script

scripts/update_asdl.sh

@@ -1,7 +0,0 @@
-#!/bin/bash
-set -e
-
-cd "$(dirname "$(dirname "$0")")"
-
-python compiler/ast/asdl_rs.py -D compiler/ast/src/ast_gen.rs -M vm/src/stdlib/ast/gen.rs compiler/ast/Python.asdl
-rustfmt compiler/ast/src/ast_gen.rs vm/src/stdlib/ast/gen.rs