Bump to ESLint 9 (#606)

This bumps to ESLint 9:

* Bump the main `eslint` package to v9
* Remove the `eslint-config-standard` package as it doesn't yet support
  ESLint 9 and doesn't appear to be actively maintained... I considered
  some of the alternatives, but they've got some drama attached (https://github.com/standard/standard/issues/1948)
  so it seemed simplest for now to not worry about replacing it. This is
  a linter, so it's easy to switch to a different config if we want to
  later.
* Migrate to the new [Flat config format](https://eslint.org/docs/user-guide/configuring/configuration-files#using-the-flat-format).

.eslintignore

@@ -1,2 +0,0 @@
-node_modules
-dist

.eslintrc.js

@@ -1,20 +0,0 @@
-module.exports = {
-  env: {
-    browser: true,
-    commonjs: true,
-    es2021: true,
-    jest: true,
-  },
-  extends: [
-    'standard'
-  ],
-  parser: '@typescript-eslint/parser',
-  parserOptions: {
-    ecmaVersion: 12
-  },
-  plugins: [
-    '@typescript-eslint'
-  ],
-  rules: {
-  }
-}

eslint.config.mjs

@@ -0,0 +1,42 @@
+import { defineConfig } from "eslint/config";
+import typescriptEslint from "@typescript-eslint/eslint-plugin";
+import globals from "globals";
+import tsParser from "@typescript-eslint/parser";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import js from "@eslint/js";
+import { FlatCompat } from "@eslint/eslintrc";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const compat = new FlatCompat({
+    baseDirectory: __dirname,
+    recommendedConfig: js.configs.recommended,
+    allConfig: js.configs.all
+});
+
+export default defineConfig([{
+    plugins: {
+        "@typescript-eslint": typescriptEslint,
+    },
+    languageOptions: {
+        globals: {
+            ...globals.browser,
+            ...globals.commonjs,
+            ...globals.jest,
+        },
+        parser: tsParser,
+        ecmaVersion: 12,
+        sourceType: "script",
+    },
+    rules: {},
+}, {
+    ignores: [
+        'dist/',
+        'lib/',
+        'node_modules/',
+        'jest.config.js',
+        'repo/',
+        'output/',
+    ],
+}]);

package.json

@@ -28,18 +28,20 @@
     "pluralize": "^8.0.0"
   },
   "devDependencies": {
+    "@eslint/eslintrc": "^3.3.0",
+    "@eslint/js": "^9.22.0",
     "@types/jest": "^29.5.12",
     "@types/node": "^20.11.20",
     "@types/yargs": "^17.0.32",
-    "@typescript-eslint/eslint-plugin": "^7.0.2",
-    "@typescript-eslint/parser": "^7.0.2",
+    "@typescript-eslint/eslint-plugin": "^8.27.0",
+    "@typescript-eslint/parser": "^8.27.0",
     "@vercel/ncc": "^0.38.3",
     "dotenv": "^16.4.5",
-    "eslint": "^8.50.0",
-    "eslint-config-standard": "^17.1.0",
-    "eslint-plugin-import": "^2.29.1",
+    "eslint": "^9.22.0",
+    "eslint-plugin-import": "^2.31.0",
     "eslint-plugin-node": "^11.1.0",
-    "eslint-plugin-promise": "^6.1.1",
+    "eslint-plugin-promise": "^7.2.1",
+    "globals": "^16.0.0",
     "jest": "^29.7.0",
     "nock": "^13.5.3",
     "ts-jest": "^29.1.2",