feat: drop ESLint v3, v4, v5, v6 & v7 support#3846

MichaelDeBoey wants to merge 2 commits intojsx-eslint:masterjsx-eslint/eslint-plugin-react:masterfrom

MichaelDeBoey:drop-ESLint-3-4-5-6-7-supportMichaelDeBoey/eslint-plugin-react:drop-ESLint-3-4-5-6-7-supportCopy head branch name to clipboard