Bump appengine from 0.13.5 to 0.13.6 in /auto_submit (#2946)

Bumps [appengine](https://github.com/dart-lang/appengine) from 0.13.5 to 0.13.6.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/dart-lang/appengine/blob/master/CHANGELOG.md">appengine's changelog</a>.</em></p>
<blockquote>
<h2>0.13.6</h2>
<ul>
<li>Require Dart 2.19.</li>
<li>Setup <code>dbService</code> to do retries for failed requests.</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/dart-lang/appengine/commit/193cca6d98ddb1aabac23c211ef3bc36c2f4903a"><code>193cca6</code></a> Prepare 0.13.6 with retries for datastore (<a href="https://redirect.github.com/dart-lang/appengine/issues/167">#167</a>)</li>
<li><a href="https://github.com/dart-lang/appengine/commit/002720bb12be6bd18a3399049d073894f5f86a9b"><code>002720b</code></a> Bump actions/checkout from 3.5.2 to 3.5.3 (<a href="https://redirect.github.com/dart-lang/appengine/issues/166">#166</a>)</li>
<li><a href="https://github.com/dart-lang/appengine/commit/efae5f923c72bba8d73f6a75cf47900d79ea7a0a"><code>efae5f9</code></a> update terminology used in the protos (<a href="https://redirect.github.com/dart-lang/appengine/issues/164">#164</a>)</li>
<li><a href="https://github.com/dart-lang/appengine/commit/be15c9e1583d6342e349a81d54b90e4ea4ddafa5"><code>be15c9e</code></a> blast_repo fixes (<a href="https://redirect.github.com/dart-lang/appengine/issues/163">#163</a>)</li>
<li><a href="https://github.com/dart-lang/appengine/commit/ef535b62b2f15105815e466e33c18bc5234fbe69"><code>ef535b6</code></a> Bump actions/checkout from 3.5.0 to 3.5.2 (<a href="https://redirect.github.com/dart-lang/appengine/issues/161">#161</a>)</li>
<li>See full diff in <a href="https://github.com/dart-lang/appengine/compare/0.13.5...0.13.6">compare view</a></li>
</ul>
</details>
<br />

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</details>

auto_submit/pubspec.yaml

@@ -11,7 +11,7 @@ environment:
   sdk: '>=3.0.0 <4.0.0'
 
 dependencies:
-  appengine: 0.13.5
+  appengine: 0.13.6
   corsac_jwt: 1.0.0-nullsafety.1
   github: 9.16.0
   googleapis: 11.3.0