Set eslint to working version

[benmccann]

No description provided.

[kurkle]

eslint seems to evolve rapidly. How about ^5.0.0?

[benmccann]

I want to avoid getting the latest version of eslint because Chart.js is broken with it. If you run rm -rf node_modules package-lock.json then npm install and gulp lint it will fail. The latest commits on master are broken and this is an attempt to get our build back into a working state. We should figure out what the eslint or gulp-eslint issue is and fix it, but in the meantime I'd like to make sure Chart.js still works for everyone

[simonbrunel]

Related to BenoitZugmeyer/eslint-plugin-html#113 and certainly fixed by BenoitZugmeyer/eslint-plugin-html#112

[benmccann]

Ok. Closing this since the latest version is a working version. #6040 will need to be merged to fix the build