Can’t override sourceType for a .ts file

[andersk]

#544 fixed "sourceType": "script" for a .js file, but not for a .ts file:

{
  "dependencies": {
    "xo": "^0.40.1"
  },
  "xo": {
    "parserOptions": {
      "sourceType": "script"
    }
  }
}

$ xo --print-config foo.js | grep sourceType
		"sourceType": "script",
$ xo --print-config foo.ts | grep sourceType
		"sourceType": "module",

(Worked in 0.39, with "script" or "module".)