Bump virtualenv from 20.11.2 to 20.12.0 in /.github/workflows (#131)

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.11.2 to 20.12.0.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst">virtualenv's changelog</a>.</em></p>
<blockquote>
<h2>v20.12.0 (2021-12-31)</h2>
<p>Features - 20.12.0</p>
<pre><code>- Sign the python2 exe on Darwin arm64 - by :user:`tmspicer`. (`[#2233](pypa/virtualenv#2233) &lt;https://github.com/pypa/virtualenv/issues/2233&gt;`_)
<p>Bugfixes - 20.12.0
</code></pre></p>
<ul>
<li>Fix <code>--download</code> option - by :user:<code>mayeut</code>. (<code>[#2120](pypa/virtualenv#2120) &lt;https://github.com/pypa/virtualenv/issues/2120&gt;</code>_)</li>
<li>Ugrade embedded setuptools to <code>60.2.0</code> from <code>60.1.1</code> - by :user:<code>gaborbernat</code>. (<code>[#2263](pypa/virtualenv#2263) &lt;https://github.com/pypa/virtualenv/issues/2263&gt;</code>_)</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/pypa/virtualenv/commit/232a0b644471bd26ed3147404df1bc018fc5a097"><code>232a0b6</code></a> release 20.12.0</li>
<li><a href="https://github.com/pypa/virtualenv/commit/614b023492f66b07ae96716c308f1560f7ce5230"><code>614b023</code></a> Bump embed setuptools (<a href="https://github-redirect.dependabot.com/pypa/virtualenv/issues/2263">#2263</a>)</li>
<li><a href="https://github.com/pypa/virtualenv/commit/f7ababdf0be4db3625444bbb20fa268a3885e645"><code>f7ababd</code></a> Sign the python2 exe on Darwin arm64 (<a href="https://github-redirect.dependabot.com/pypa/virtualenv/issues/2233">#2233</a>)</li>
<li><a href="https://github.com/pypa/virtualenv/commit/61c065ba7731b65bdc15af7900aa530963695868"><code>61c065b</code></a> fix: <code>--download</code> option (<a href="https://github-redirect.dependabot.com/pypa/virtualenv/issues/2262">#2262</a>)</li>
<li><a href="https://github.com/pypa/virtualenv/commit/b17dcd4ce1f608059448566fb3e929e911d8bf43"><code>b17dcd4</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/pypa/virtualenv/issues/2261">#2261</a> from pypa/release-20.11.2</li>
<li>See full diff in <a href="https://github.com/pypa/virtualenv/compare/20.11.2...20.12.0">compare view</a></li>
</ul>
</details>
<br />


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.github/workflows/constraints.txt

@@ -2,4 +2,4 @@ pip==21.3.1
 nox==2021.10.1
 nox-poetry==0.9.0
 poetry==1.1.12
-virtualenv==20.11.2
+virtualenv==20.12.0