build(deps-dev): bump grunt-contrib-concat in /src/tools/website

Bumps [grunt-contrib-concat](https://github.com/gruntjs/grunt-contrib-concat) from 1.0.1 to 2.1.0.
- [Release notes](https://github.com/gruntjs/grunt-contrib-concat/releases)
- [Changelog](https://github.com/gruntjs/grunt-contrib-concat/blob/main/CHANGELOG)
- [Commits](gruntjs/grunt-contrib-concat@v1.0.1...v2.1.0)

---
updated-dependencies:
- dependency-name: grunt-contrib-concat
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

src/tools/website/package-lock.json

@@ -39,7 +39,7 @@
         "grunt": "^1.3.0",
         "grunt-browserify": "^6.0.0",
         "grunt-cli": "latest",
-        "grunt-contrib-concat": "^1.0.1",
+        "grunt-contrib-concat": "^2.1.0",
         "grunt-contrib-connect": "^3.0.0",
         "grunt-contrib-copy": "^1.0.0",
         "grunt-contrib-cssmin": "latest",