Update node to 18.x in CI

.github/workflows/node.js.yml

@@ -16,8 +16,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Use Node.js 15.x
+    - name: Use Node.js 18.x
       uses: actions/setup-node@v1
       with:
-        node-version: '15.x'
+        node-version: '18.x'
     - run: npm ci # This will automatically build and run tests because the prepublish step is to run `gulp`

gulpfile.js

@@ -1,13 +1,13 @@
-import { task, src, dest, series, parallel } from "gulp";
-import mocha from "gulp-mocha";
-import json2cson from "gulp-json2cson";
-import yaml from "gulp-yaml";
-import { createProject } from "gulp-typescript";
-import { load } from "js-yaml";
-import { build } from "plist";
-import { readFileSync, existsSync, mkdirSync, writeFileSync } from "fs";
-import { join } from "path";
-import { exec } from "child_process";
+const gulp = import("gulp");
+const mocha = require("gulp-mocha");
+const json2cson = require("gulp-json2cson");
+const yaml = require("gulp-yaml");
+const ts = require("gulp-typescript");
+const js_yaml = require("js-yaml");
+const plist = require("plist");
+const fs = require("fs");
+const path = require("path");
+const exec = require("child_process").exec;
 
 const inputGrammar = "src/csharp.tmLanguage.yml";
 const grammarsDirectory = "grammars/";