Bump numpy from 1.21.3 to 1.21.4 (#81)

Bumps [numpy](https://github.com/numpy/numpy) from 1.21.3 to 1.21.4.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/numpy/numpy/releases">numpy's releases</a>.</em></p>
<blockquote>
<h2>v1.21.4</h2>
<h1>NumPy 1.21.4 Release Notes</h1>
<p>The NumPy 1.21.4 is a maintenance release that fixes a few bugs
discovered after 1.21.3. The most important fix here is a fix for the
NumPy header files to make them work for both x86_64 and M1 hardware
when included in the Mac universal2 wheels. Previously, the header files
only worked for M1 and this caused problems for folks building x86_64
extensions. This problem was not seen before Python 3.10 because there
were thin wheels for x86_64 that had precedence. This release also
provides thin x86_64 Mac wheels for Python 3.10.</p>
<p>The Python versions supported in this release are 3.7-3.10. If you want
to compile your own version using gcc-11, you will need to use gcc-11.2+
to avoid problems.</p>
<h2>Contributors</h2>
<p>A total of 7 people contributed to this release. People with a &quot;+&quot; by
their names contributed a patch for the first time.</p>
<ul>
<li>Bas van Beek</li>
<li>Charles Harris</li>
<li>Isuru Fernando</li>
<li>Matthew Brett</li>
<li>Sayed Adel</li>
<li>Sebastian Berg</li>
<li>傅立业（Chris Fu） +</li>
</ul>
<h2>Pull requests merged</h2>
<p>A total of 9 pull requests were merged for this release.</p>
<ul>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20278">#20278</a>: BUG: Fix shadowed reference of <code>dtype</code> in type stub</li>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20293">#20293</a>: BUG: Fix headers for universal2 builds</li>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20294">#20294</a>: BUG: <code>VOID_nonzero</code> could sometimes mutate alignment flag</li>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20295">#20295</a>: BUG: Do not use nonzero fastpath on unaligned arrays</li>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20296">#20296</a>: BUG: Distutils patch to allow for 2 as a minor version (!)</li>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20297">#20297</a>: BUG, SIMD: Fix 64-bit/8-bit integer division by a scalar</li>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20298">#20298</a>: BUG, SIMD: Workaround broadcasting SIMD 64-bit integers on MSVC...</li>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20300">#20300</a>: REL: Prepare for the NumPy 1.21.4 release.</li>
<li><a href="https://github-redirect.dependabot.com/numpy/numpy/pull/20302">#20302</a>: TST: Fix a <code>Arrayterator</code> typing test failure</li>
</ul>
<h2>Checksums</h2>
<h3>MD5</h3>

</blockquote>
<p>... (truncated)</p>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/numpy/numpy/commit/c0b003e9c787ccab27f6fe57c154d7b881da5795"><code>c0b003e</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/numpy/numpy/issues/20304">#20304</a> from charris/prepare-1.21.4-release-2</li>
<li><a href="https://github.com/numpy/numpy/commit/0a7fba9722868a3bf4c1d0032e76c1378a09218b"><code>0a7fba9</code></a> REL: Prepare for NumPy 1.21.4 release (2)</li>
<li><a href="https://github.com/numpy/numpy/commit/5d3c424dbc10bb21aeb7d8f9feb6ee2fc305e0d9"><code>5d3c424</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/numpy/numpy/issues/20302">#20302</a> from BvB93/arrayterator2</li>
<li><a href="https://github.com/numpy/numpy/commit/f9dce44e5f2358b244b051d49a2e6140adf25948"><code>f9dce44</code></a> TST: Fix a <code>Arrayterator</code> typing test failure</li>
<li><a href="https://github.com/numpy/numpy/commit/1584f129a8b701fcf464c1af3fbe7dba55f7fe66"><code>1584f12</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/numpy/numpy/issues/20300">#20300</a> from charris/prepare-1.21.4-release</li>
<li><a href="https://github.com/numpy/numpy/commit/0eab6bb433c5aca4be5663f9e1ee0feb9a636cc3"><code>0eab6bb</code></a> REL: Prepare for the NumPy 1.21.4 release.</li>
<li><a href="https://github.com/numpy/numpy/commit/b134e90b5ba19f118c9e5184708e0169009abf81"><code>b134e90</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/numpy/numpy/issues/20293">#20293</a> from charris/backport-20270</li>
<li><a href="https://github.com/numpy/numpy/commit/acbbf1a66179f8c83c75022ddbdbf1d15c35cdaa"><code>acbbf1a</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/numpy/numpy/issues/20294">#20294</a> from charris/backport-20237</li>
<li><a href="https://github.com/numpy/numpy/commit/5fe9833b45772a36e4c324c1ff59cc2926dae1be"><code>5fe9833</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/numpy/numpy/issues/20295">#20295</a> from charris/backport-20179</li>
<li><a href="https://github.com/numpy/numpy/commit/496c9c064bb3e7b0c66e1774d7849514b9981e3c"><code>496c9c0</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/numpy/numpy/issues/20296">#20296</a> from charris/backport-20155</li>
<li>Additional commits viewable in <a href="https://github.com/numpy/numpy/compare/v1.21.3...v1.21.4">compare view</a></li>
</ul>
</details>
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