Fixed compatibility with latest Webpack

As of webpack/webpack@5acfacf `.Class`
webpack is using `Dependency::constructor` over `Dependency::Class`. I
decided to keep the `.Class` for backwards compatibility.

Fixes #16

lib/RewiredDependency.js

@@ -12,6 +12,7 @@ function RewiredDependency(request, range) {
 
 RewiredDependency.prototype = Object.create(Dependency.prototype);
 RewiredDependency.prototype.type = "rewire";
+RewiredDependency.prototype.constructor = RewiredDependency;
 RewiredDependency.prototype.isEqualResource = function (other) {
     return other instanceof RewiredDependency?
             this.request === other.request:
@@ -20,4 +21,4 @@ RewiredDependency.prototype.isEqualResource = function (other) {
 
 RewiredDependency.Template = require("webpack/lib/dependencies/ModuleDependencyTemplateAsId.js");
 
-module.exports = RewiredDependency;
+module.exports = RewiredDependency;