[turtle-cli] don't require gulp-cli installed globally

package.json

@@ -1,6 +1,6 @@
 {
   "name": "turtle-cli",
-  "version": "0.8.3",
+  "version": "0.8.4",
   "description": "The command-line tool for building standalone Expo apps",
   "preferGlobal": true,
   "scripts": {

src/bin/setup/android/index.ts

@@ -20,10 +20,6 @@ const REQUIRED_TOOLS: IToolDefinition[] = [
     command: 'bash',
     missingDescription: 'Please install bash',
   },
-  {
-    command: 'gulp',
-    missingDescription: 'Run `npm install -g gulp-cli` (or `yarn global add gulp-cli`) to install gulp',
-  },
   {
     command: 'javac',
     missingDescription: 'Please install JDK (version 8 or newer) - check https://jdk.java.net/',