bison: bump `%require` version

* src/parse/asm-parse.yy.gen.py: Here.

src/parse/asm-parse.yy.gen.py

@@ -55,7 +55,7 @@ print ("""
 using namespace inst;
 %}
 
-%require "2.1a"
+%require "3.0"
 %skeleton "lalr1.cc"
 %define parse.error verbose
 %defines