Update ESLint configuration to flat format (#477)

Author: Fryuni

eslint.config.js

@@ -0,0 +1,19 @@
+import { defineConfig } from 'eslint/config';
+import eslintPlugin from 'eslint-plugin-eslint-plugin';
+import { configs } from './dist/index.js';
+
+export default defineConfig(
+    configs.typescript,
+    eslintPlugin.configs['flat/recommended'],
+    {
+        files: ['src/**/*.ts'],
+        rules: {
+            '@typescript-eslint/explicit-function-return-type': 'off',
+            // Many casts are necessary to account for libraries maintaining compatibility between v8 and v9
+            '@typescript-eslint/no-unsafe-assignment': 'off',
+            '@typescript-eslint/no-unsafe-member-access': 'off',
+            // ESLint plugin development expects default exports
+            'import-x/no-default-export': 'off',
+        },
+    },
+);