Time out requesting http://localhost:8081/onchange on iOS

## Environment

```
System:
OS: macOS 10.15.4
CPU: (8) x64 Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
Memory: 781.97 MB / 16.00 GB
Shell: 3.2.57 - /bin/bash
Binaries:
Node: 12.16.3 - /usr/local/opt/node@12/bin/node
Yarn: 1.22.4 - /usr/local/bin/yarn
npm: 6.14.4 - /usr/local/opt/node@12/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
SDKs:
iOS SDK:
Platforms: iOS 13.4, DriverKit 19.0, macOS 10.15, tvOS 13.4, watchOS 6.2
Android SDK:
API Levels: 26, 27, 28, 29
Build Tools: 28.0.3, 29.0.3
System Images: android-28 | Google APIs Intel x86 Atom
Android NDK: 20.0.5594570
IDEs:
Android Studio: 3.6 AI-192.7142.36.36.6392135
Xcode: 11.4.1/11E503a - /usr/bin/xcodebuild
npmPackages:
@haul-bundler/cli: 0.19.0 => 0.19.0
react-native: 0.60.6 => 0.60.6
npmGlobalPackages:
react-native-cli: 2.0.1
```

## Description

If you leave Haul open for a while without doing anything, you'll get a bunch of `The request timed out.` errors because it keeps trying to fetch `http://localhost:8081/onchange`. The terminal will be filled with `/onchange`:

```
...
info ► GET /onchange
info ► GET /onchange
info ► GET /onchange
info ► GET /onchange
```

And in Xcode, you'll see many lines like below:

`2020-05-25 22:53:57.020315+0200 ReactTestApp[90320:10851273] Task <0D3B9BB0-F2B1-4C7D-804A-16E2B0D83494>.<20> finished with error [-1001] Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." UserInfo={NSUnderlyingError=0x600002038300 {Error Domain=kCFErrorDomainCFNetwork Code=-1001 "(null)" UserInfo={_kCFStreamErrorCodeKey=-2102, _kCFStreamErrorDomainKey=4}}, NSErrorFailingURLStringKey=http://localhost:8081/onchange, NSErrorFailingURLKey=http://localhost:8081/onchange, _kCFStreamErrorDomainKey=4, _kCFStreamErrorCodeKey=-2102, NSLocalizedDescription=The request timed out.}`

FWIW, I don't think that anything's broken. It's more of an annoyance.

## Reproduction Steps

1. Start Haul in watch mode
2. Start any RN app and enable "Live Reload"
3. Wait…