Migrate ESLint to flat config

See:
- https://eslint.org/blog/2022/08/new-config-system-part-2
- https://eslint.org/docs/latest/use/configure/migration-guide
- https://typescript-eslint.io/getting-started

.gitattributes

@@ -1,2 +1 @@
-.eslintrc linguist-language=JSON
 .prettierrc linguist-language=JSON

.github/workflows/nodejs.yml

@@ -26,7 +26,7 @@ jobs:
       - name: Check formatting with Prettier
         run: npx prettier --check --ignore-unknown "**/*"
       - name: Lint with ESLint
-        run: npx eslint . --ext .ts
+        run: npx eslint "**/*.ts" eslint.config.mjs
       - name: Test with Mocha
         run: npx mocha -r ts-node/register "**/*.spec.ts"
         working-directory: nodejs

.prettierrc

@@ -3,7 +3,7 @@
   "bracketSpacing": false,
   "overrides": [
     {
-      "files": [".eslintrc", ".prettierrc"],
+      "files": ".prettierrc",
       "options": {"parser": "json"}
     }
   ]

eslint.config.mjs

@@ -0,0 +1,8 @@
+// @ts-check
+import eslint from "@eslint/js";
+import tseslint from "typescript-eslint";
+
+export default tseslint.config(
+  eslint.configs.recommended,
+  ...tseslint.configs.recommended
+);

package.json

@@ -1,15 +1,16 @@
 {
   "private": true,
   "devDependencies": {
+    "@eslint/js": "9.6.0",
+    "@types/eslint__js": "8.42.3",
     "@types/mocha": "10.0.7",
     "@types/node": "20.14.9",
-    "@typescript-eslint/eslint-plugin": "7.14.1",
-    "@typescript-eslint/parser": "7.14.1",
     "eslint": "8.57.0",
     "mocha": "10.5.2",
     "prettier": "3.3.2",
     "ts-node": "10.9.2",
     "typescript": "5.5.2",
+    "typescript-eslint": "7.14.1",
     "pulumi-aws-tags": "file:nodejs"
   }
 }