Merge #469

469: build(deps): bump attrs from 21.3.0 to 21.4.0 r=ChrisRBe a=dependabot[bot]

Bumps [attrs](https://github.com/python-attrs/attrs) from 21.3.0 to 21.4.0.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/python-attrs/attrs/releases">attrs's releases</a>.</em></p>
<blockquote>
<h2>21.4.0</h2>
<p>This is a quick bug fix release for a regression that causes <code>coverage report</code> fail under certain circumstances.</p>
<h1>Full Changelog</h1>
<h2>Changes</h2>
<ul>
<li>Fixed the test suite on PyPy3.8 where <code>cloudpickle</code> does not work. <a href="https://github-redirect.dependabot.com/python-attrs/attrs/issues/892">#892</a></li>
<li>Fixed <code>coverage report</code> for projects that use <code>attrs</code> and don't set a <code>--source</code>. <a href="https://github-redirect.dependabot.com/python-attrs/attrs/issues/895">#895</a>, <a href="https://github-redirect.dependabot.com/python-attrs/attrs/issues/896">#896</a></li>
</ul>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/python-attrs/attrs/blob/main/CHANGELOG.rst">attrs's changelog</a>.</em></p>
<blockquote>
<h2>21.4.0 (2021-12-29)</h2>
<p>Changes
^^^^^^^</p>
<ul>
<li>Fixed the test suite on PyPy3.8 where <code>cloudpickle</code> does not work.
<code>[#892](python-attrs/attrs#892) &lt;https://github.com/python-attrs/attrs/issues/892&gt;</code>_</li>
<li>Fixed <code>coverage report</code> for projects that use <code>attrs</code> and don't set a <code>--source</code>.
<code>[#895](python-attrs/attrs#895) &lt;https://github.com/python-attrs/attrs/issues/895&gt;</code><em>,
<code>[#896](python-attrs/attrs#896) &lt;https://github.com/python-attrs/attrs/issues/896&gt;</code></em></li>
</ul>
<hr />
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/python-attrs/attrs/commit/2de90143100e713d8ae6b5d1adb5e1e879af01fb"><code>2de9014</code></a> Prepare 21.4.0</li>
<li><a href="https://github.com/python-attrs/attrs/commit/02ba249b81a8d01ef6e7b04a7412556234aaa3bb"><code>02ba249</code></a> Remove dead anchors</li>
<li><a href="https://github.com/python-attrs/attrs/commit/1ff3f1ee919178946bb48442f1e183ea99dae373"><code>1ff3f1e</code></a> Minor changelog polish</li>
<li><a href="https://github.com/python-attrs/attrs/commit/0575d51ffddc0de465e7229571d11f9c6f6b8575"><code>0575d51</code></a> Make virtual repr file names unique (<a href="https://github-redirect.dependabot.com/python-attrs/attrs/issues/896">#896</a>)</li>
<li><a href="https://github.com/python-attrs/attrs/commit/03dd7136cf1ccc58c9612531ba9711892830c1fb"><code>03dd713</code></a> Do not require cloudpickle for PyPy (<a href="https://github-redirect.dependabot.com/python-attrs/attrs/issues/892">#892</a>)</li>
<li><a href="https://github.com/python-attrs/attrs/commit/ce50f40b52567564000af685959dc6df97c5f384"><code>ce50f40</code></a> Use correct words</li>
<li><a href="https://github.com/python-attrs/attrs/commit/9424a930f966ade789b1ea4b8043efe916c50769"><code>9424a93</code></a> Tell coverage about import attrs</li>
<li><a href="https://github.com/python-attrs/attrs/commit/c86fbc864862983111184eb9c3092afe2f2d477e"><code>c86fbc8</code></a> Use better word</li>
<li><a href="https://github.com/python-attrs/attrs/commit/7695908aa7b4a96fbfefb7432145f843ae9c0c98"><code>7695908</code></a> docs: fix very minor typo (<a href="https://github-redirect.dependabot.com/python-attrs/attrs/issues/894">#894</a>)</li>
<li><a href="https://github.com/python-attrs/attrs/commit/ada66bef24700d159acff4b72b7cb34a263ccccf"><code>ada66be</code></a> docs: remove typo in README.rst (<a href="https://github-redirect.dependabot.com/python-attrs/attrs/issues/893">#893</a>)</li>
<li>Additional commits viewable in <a href="https://github.com/python-attrs/attrs/compare/21.3.0...21.4.0">compare view</a></li>
</ul>
</details>
<br />


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requirements.txt

@@ -1,7 +1,7 @@
 appdirs==1.4.4
 astroid==2.9.0
 atomicwrites==1.4.0
-attrs==21.3.0
+attrs==21.4.0
 black==21.4b2
 certifi==2021.10.8
 cfgv==3.3.1