Convert to flat config

Author: khiga8

.eslintrc.json

@@ -0,0 +1,28 @@
+import github from "eslint-plugin-github";
+import globals from "globals";
+
+export default [
+  github.getFlatConfigs().recommended,
+  {
+    languageOptions: {
+      ecmaVersion: 13,
+      globals: {
+        ...globals.es6,
+        ...globals.node,
+        ...globals.jest,
+      },
+    },
+    files: ["**/*.{js,mjs,cjs,jsx,mjsx,ts,tsx,mtsx}"],
+    rules: {
+      "github/filenames-match-regex": "off",
+      "i18n-text/no-en": "off",
+      "import/extensions": ["error", { js: "ignorePackages" }],
+      "import/no-unresolved": [
+        "error",
+        {
+          ignore: ["^markdownlint/.+"],
+        },
+      ],
+    },
+  },
+];