Bump grunt from 1.5.2 to 1.5.3 (#549)

Bumps [grunt](https://github.com/gruntjs/grunt) from 1.5.2 to 1.5.3.
- [Release notes](https://github.com/gruntjs/grunt/releases)
- [Changelog](https://github.com/gruntjs/grunt/blob/main/CHANGELOG)
- [Commits](gruntjs/grunt@v1.5.2...v1.5.3)

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

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -28,7 +28,7 @@
     "chai-as-promised": "^7.1.1",
     "eslint-config-google": "^0.11.0",
     "eslint-config-webrtc": "^1.0.0",
-    "grunt": "^1.5.2",
+    "grunt": "^1.5.3",
     "grunt-browserify": "^6.0.0",
     "grunt-cli": "^1.3.2",
     "grunt-contrib-clean": "~2.0.0",