build: Update devDependencies

 eslint-config-wikimedia      0.5.0  →   0.8.1
 grunt-eslint                20.1.0  →  21.0.0
 grunt-stylelint              0.9.0  →  0.10.1
 stylelint                    8.2.0  →   9.2.0
 stylelint-config-wikimedia   0.4.2  →   0.4.3

Change-Id: Ic43469c7d71af970920d00e0864fc0a503d8e294
3 files changed