chore: upgrade to eslint v9

eslint.config.mjs

@@ -0,0 +1,40 @@
+// @ts-check
+import eslint from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended';
+import globals from 'globals';
+
+export default tseslint.config(
+  {
+    ignores: ['eslint.config.mjs', 'src/**/*.test.ts', 'src/**/files/**', 'test/**'],
+  },
+  eslint.configs.recommended,
+  ...tseslint.configs.recommendedTypeChecked,
+  eslintPluginPrettierRecommended,
+  {
+    languageOptions: {
+      globals: {
+        ...globals.node,
+        ...globals.jest,
+      },
+      ecmaVersion: 5,
+      sourceType: 'module',
+      parserOptions: {
+        projectService: true,
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+  },
+  {
+    rules: {
+      '@typescript-eslint/interface-name-prefix': 'off',
+      '@typescript-eslint/explicit-function-return-type': 'off',
+      '@typescript-eslint/explicit-module-boundary-types': 'off',
+      '@typescript-eslint/no-explicit-any': 'off',
+      '@typescript-eslint/no-unsafe-assignment': 'off',
+      '@typescript-eslint/no-require-imports': 'off',
+      '@typescript-eslint/no-unsafe-call': 'off',
+      '@typescript-eslint/no-unsafe-member-access': 'off',
+    },
+  },
+);