Fix CI to correctly use the right tslib in webpack 5

Author: orta

test/rollup-modules/index.js

@@ -1,2 +1,2 @@
-import { __awaiter } from "tslib";
+import { __awaiter } from "../../";
 if (typeof __awaiter !== "function") throw new Error("Missing expected helper __awaiter");

test/webpack-5-modules/package.json

@@ -3,6 +3,7 @@
     "test": "webpack && node build/main.js"
   },
   "devDependencies": {
+    "tslib": "file:../..",
     "webpack": "5.0.0-rc.4",
     "webpack-cli": "3.3.12"
   }