Bump boto3 from 1.21.17 to 1.21.18 (#234)

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Bumps [boto3](https://github.com/boto/boto3) from 1.21.17 to 1.21.18.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/boto/boto3/blob/develop/CHANGELOG.rst">boto3's changelog</a>.</em></p>
<blockquote>
<h1>1.21.18</h1>
<ul>
<li>api-change:<code>outposts</code>: [<code>botocore</code>] This release adds address filters for listSites</li>
<li>api-change:<code>lambda</code>: [<code>botocore</code>] Adds PrincipalOrgID support to AddPermission API. Customers can use it to manage permissions to lambda functions at AWS Organizations level.</li>
<li>api-change:<code>secretsmanager</code>: [<code>botocore</code>] Documentation updates for Secrets Manager.</li>
<li>api-change:<code>connect</code>: [<code>botocore</code>] This release adds support for enabling Rich Messaging when starting a new chat session via the StartChatContact API. Rich Messaging enables the following formatting options: bold, italics, hyperlinks, bulleted lists, and numbered lists.</li>
<li>api-change:<code>chime</code>: [<code>botocore</code>] Chime VoiceConnector Logging APIs will now support MediaMetricLogs. Also CreateMeetingDialOut now returns AccessDeniedException.</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/boto/boto3/commit/97069c53390424f4dbb5dfbd0fb50978c0fa650e"><code>97069c5</code></a> Merge branch 'release-1.21.18'</li>
<li><a href="https://github.com/boto/boto3/commit/8c350e5231c3973de58fabe05f959c40acfa1f6d"><code>8c350e5</code></a> Bumping version to 1.21.18</li>
<li><a href="https://github.com/boto/boto3/commit/6b028241ec86dcdf5d6904f2e9f33230018c58b0"><code>6b02824</code></a> Add changelog entries from botocore</li>
<li><a href="https://github.com/boto/boto3/commit/da4cb3ed2ac9f133888e273dee1199ef99c47240"><code>da4cb3e</code></a> Merge branch 'release-1.21.17' into develop</li>
<li>See full diff in <a href="https://github.com/boto/boto3/compare/1.21.17...1.21.18">compare view</a></li>
</ul>
</details>
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</details>