refactor: remove use strict directives (redundant in modules)

Author: brettz9

index.js

@@ -1,5 +1,3 @@
-'use strict';
-
 import * as acorn from "acorn";
 import XHTMLEntities from './xhtml';
 

test/tests-misc.js

@@ -1,5 +1,3 @@
-"use strict";
-
 import assert from "assert";
 import * as acorn from "acorn";
 import jsx from "../index.js";