Bump rollup from 0.25.8 to 2.79.2 in /packages/web-component-tester

Bumps [rollup](https://github.com/rollup/rollup) from 0.25.8 to 2.79.2.
- [Release notes](https://github.com/rollup/rollup/releases)
- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
- [Commits](rollup/rollup@v0.25.8...v2.79.2)

---
updated-dependencies:
- dependency-name: rollup
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

packages/web-component-tester/package.json

@@ -112,7 +112,7 @@
     "gulp-tslint": "^8.1.2",
     "gulp-typescript": "^3.1.2",
     "rimraf": "^2.5.4",
-    "rollup": "^0.25.1",
+    "rollup": "^2.79.2",
     "source-map-support": "^0.5.4",
     "watch": "^0.18.0",
     "wct-local": "^2.1.1",