Bump go_router from 15.1.3 to 16.1.0 in /testing_app (#2712)

Bumps [go_router](https://github.com/flutter/packages/tree/main/packages) from 15.1.3 to 16.1.0.
<details>
<summary>Commits</summary>
<ul>
<li><a href="83ae18a4fa"><code>83ae18a</code></a> [go_router] add initial json support <a href="https://github.com/flutter/packages/tree/main/packages/issues/110781">#110781</a> (<a href="https://github.com/flutter/packages/tree/main/packages/issues/9404">#9404</a>)</li>
<li><a href="56bcd0cbbf"><code>56bcd0c</code></a> [google_maps_flutter_ios] Fix kCGImageAlphaPremultipliedLast implicit convers...</li>
<li><a href="b53593053d"><code>b535930</code></a> [interactive_media_ads] Fixes setting adsresponse on Android (<a href="https://github.com/flutter/packages/tree/main/packages/issues/9744">#9744</a>)</li>
<li><a href="28c35c6e0d"><code>28c35c6</code></a> [interactive_media_ads]: Adds additional methods to configure ad requests (<a href="https://github.com/flutter/packages/tree/main/packages/issues/9">#9</a>...</li>
<li><a href="03b33b1a22"><code>03b33b1</code></a> [webview_flutter_platform_interface] Provide flexible API for loading local H...</li>
<li><a href="f0645d8448"><code>f0645d8</code></a> Mark <code>FlutterIOOverrides</code> as <code>final</code> (<a href="https://github.com/flutter/packages/tree/main/packages/issues/9719">#9719</a>)</li>
<li><a href="b2aef15c15"><code>b2aef15</code></a> [in_app_purchase_storekit] Updated comment  (<a href="https://github.com/flutter/packages/tree/main/packages/issues/9445">#9445</a>)</li>
<li><a href="fe53da20d5"><code>fe53da2</code></a> [video_player] Separate event stream from player on iOS (<a href="https://github.com/flutter/packages/tree/main/packages/issues/9700">#9700</a>)</li>
<li><a href="db6988d785"><code>db6988d</code></a> [tool] Remove web drive hot reload workaround (<a href="https://github.com/flutter/packages/tree/main/packages/issues/9704">#9704</a>)</li>
<li><a href="7a9e9ceee8"><code>7a9e9ce</code></a> Fixed Camera Switching Bug (<a href="https://github.com/flutter/packages/tree/main/packages/issues/9671">#9671</a>)</li>
<li>Additional commits viewable in <a href="https://github.com/flutter/packages/commits/go_router-v16.1.0/packages">compare view</a></li>
</ul>
</details>
<br />

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</details>

testing_app/pubspec.yaml

@@ -12,7 +12,7 @@ dependencies:
 
   cupertino_icons: ^1.0.3
   provider: ^6.0.2
-  go_router: ">=10.0.0 <16.0.0"
+  go_router: ">=10.0.0 <17.0.0"
 
 dev_dependencies:
   analysis_defaults: