Override the __close metamethod of FILE* objects

This enables the use of a Lua 5.4 feature where you can have Lua
auto-close a file when exiting a block. For example:

```
do
    local f <close> = kobold.get_config_file()
end
```

If we exit from the `do` block under any circumstances, including via an
error or return statement, the `FILE*` `f` automatically closes right
before that happens.

bridge.lua

@@ -279,6 +279,7 @@ return function(_python, _bridged)
         end
     end
     debug.getmetatable(io.stdout).__index.close = _new_close(io.stdout.close)
+    debug.getmetatable(io.stdout).__close = _new_close(io.stdout.close)
 
     ---@param filename string
     ---@return boolean