Remove dependency to gts

Based on the current config of the BudouX and google/budoux#187.

eslint.config.mjs

@@ -0,0 +1,75 @@
+import prettier from "eslint-plugin-prettier";
+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 [{
+    ignores: ["**/bundle", "**/dist", "**/module", "src/data"],
+}, ...compat.extends("eslint:recommended", "prettier"), {
+    plugins: {
+        prettier,
+    },
+
+    rules: {
+        "prettier/prettier": "error",
+        "block-scoped-var": "error",
+        eqeqeq: "error",
+        "no-var": "error",
+        "prefer-const": "error",
+        "eol-last": "error",
+        "prefer-arrow-callback": "error",
+        "no-trailing-spaces": "error",
+
+        quotes: ["warn", "single", {
+            avoidEscape: true,
+        }],
+
+        "no-restricted-properties": ["error", {
+            object: "describe",
+            property: "only",
+        }, {
+            object: "it",
+            property: "only",
+        }],
+    },
+}, ...compat.extends("plugin:@typescript-eslint/recommended").map(config => ({
+    ...config,
+    files: ["**/*.ts", "**/*.tsx"],
+})), {
+    files: ["**/*.ts", "**/*.tsx"],
+
+    languageOptions: {
+        parser: tsParser,
+        ecmaVersion: 2018,
+        sourceType: "module",
+    },
+
+    rules: {
+        "@typescript-eslint/no-non-null-assertion": "off",
+        "@typescript-eslint/no-use-before-define": "off",
+        "@typescript-eslint/no-warning-comments": "off",
+        "@typescript-eslint/no-empty-function": "off",
+        "@typescript-eslint/no-var-requires": "off",
+        "@typescript-eslint/explicit-function-return-type": "off",
+        "@typescript-eslint/explicit-module-boundary-types": "off",
+        "@typescript-eslint/ban-types": "off",
+        "@typescript-eslint/camelcase": "off",
+        "node/no-empty-function": "off",
+        "node/no-missing-import": "off",
+        "node/no-unsupported-features/es-syntax": "off",
+        "node/no-missing-require": "off",
+        "node/shebang": "off",
+        "no-dupe-class-members": "off",
+        "require-atomic-updates": "off",
+    },
+}];