Release 0.30.55

• Upgrade @ehmicky/eslint-config 15.10.27 -> 15.10.28 (36042ed)
• Fix linting (b7bb77d)
• Upgrade core-js 3.4.0 -> 3.4.1 (4bc1c1e)
• Update codecov script (85db010)
• Upgrade gulp-prettier 2.2.0 -> 2.3.0 (416608a)
• Upgrade prettier 1.18.2 -> 1.19.1 (7183fe5)