Bump grunt from 0.4.5 to 1.5.3

Bumps [grunt](https://github.com/gruntjs/grunt) from 0.4.5 to 1.5.3.
- [Release notes](https://github.com/gruntjs/grunt/releases)
- [Changelog](https://github.com/gruntjs/grunt/blob/main/CHANGELOG)
- [Commits](gruntjs/grunt@v0.4.5...v1.5.3)

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

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

package.json

@@ -7,7 +7,7 @@
     "@bower_components/bootstrap": "twbs/bootstrap-sass#~3.4.1"
   },
   "devDependencies": {
-    "grunt": "^0.4.5",
+    "grunt": "^1.5.3",
     "grunt-cli": "^0.1.13",
     "grunt-contrib-copy": "^0.8.2",
     "grunt-contrib-watch": "^0.6.1",