Upgrade to ESLint v9 support with eslint-plugin-github v6

.changeset/great-tables-decide.md

@@ -0,0 +1,5 @@
+---
+"eslint-plugin-primer-react": major
+---
+
+Upgrade to ESLint v9 support with eslint-plugin-github v6

.markdownlint-cli2.cjs

@@ -16,11 +16,11 @@ const options = githubMarkdownOpinions.init({
   'no-hard-tabs': false,
   'first-line-heading': false,
   'no-space-in-emphasis': false,
-  'blanks-around-fences': false
+  'blanks-around-fences': false,
 })
 
 module.exports = {
   config: options,
   customRules: ['@github/markdownlint-github'],
-  outputFormatters: [['markdownlint-cli2-formatter-pretty', {appendLink: true}]]
+  outputFormatters: [['markdownlint-cli2-formatter-pretty', {appendLink: true}]],
 }

eslint.config.js

@@ -0,0 +1,54 @@
+'use strict'
+
+const js = require('@eslint/js')
+const globals = require('globals')
+const github = require('eslint-plugin-github')
+
+/**
+ * @type {import('eslint').Linter.FlatConfig[]}
+ */
+module.exports = [
+  {
+    ignores: ['node_modules/**', '.git/**'],
+  },
+  js.configs.recommended,
+  github.default.getFlatConfigs().recommended,
+  {
+    languageOptions: {
+      ecmaVersion: 'latest',
+      sourceType: 'commonjs',
+      globals: {
+        ...globals.commonjs,
+        ...globals.node,
+      },
+    },
+    rules: {
+      // Override specific rules for the repository
+      'import/no-commonjs': 'off',
+      'import/no-dynamic-require': 'off', // Allow dynamic requires in tests
+      'no-shadow': 'off',
+      'no-unused-vars': [
+        'error',
+        {
+          varsIgnorePattern: '^_',
+        },
+      ],
+      'github/filenames-match-regex': 'off', // Allow various file naming patterns
+      'i18n-text/no-en': 'off', // Allow English text in this repository
+    },
+  },
+  {
+    files: ['**/*.test.js'],
+    languageOptions: {
+      globals: {
+        ...globals.jest,
+      },
+    },
+  },
+  {
+    files: ['eslint.config.js'],
+    rules: {
+      'no-undef': 'off', // Allow require() in config file
+    },
+  },
+]