Bump eslint-plugin-html from 4.0.6 to 6.1.2 in /webrtc/tools

Bumps [eslint-plugin-html](https://github.com/BenoitZugmeyer/eslint-plugin-html) from 4.0.6 to 6.1.2.
- [Release notes](https://github.com/BenoitZugmeyer/eslint-plugin-html/releases)
- [Changelog](https://github.com/BenoitZugmeyer/eslint-plugin-html/blob/master/CHANGELOG.md)
- [Commits](BenoitZugmeyer/eslint-plugin-html@v4.0.6...v6.1.2)

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

webrtc/tools/package.json

@@ -7,7 +7,7 @@
   },
   "devDependencies": {
     "eslint": "^4.11.0",
-    "eslint-plugin-html": "^4.0.0",
+    "eslint-plugin-html": "^6.1.2",
     "jscodeshift": "^0.5.1",
     "jsdom": "^11.11.0"
   },