chore(deps-dev): Bump postcss from 8.5.11 to 8.5.12 (#1846)

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Bumps [postcss](https://github.com/postcss/postcss) from 8.5.11 to
8.5.12.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/postcss/postcss/releases">postcss's
releases</a>.</em></p>
<blockquote>
<h2>8.5.12</h2>
<ul>
<li>Fixed reading any file via user-generated CSS.</li>
<li>Added <code>opts.unsafeMap</code> to disable checks.</li>
</ul>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/postcss/postcss/blob/main/CHANGELOG.md">postcss's
changelog</a>.</em></p>
<blockquote>
<h2>8.5.12</h2>
<ul>
<li>Fixed reading any file via user-generated CSS.</li>
<li>Added <code>opts.unsafeMap</code> to disable checks.</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/postcss/postcss/commit/9bc81c48f054a630c9a2e3868263b7ad4fc15013"><code>9bc81c4</code></a>
Release 8.5.12 version</li>
<li><a
href="https://github.com/postcss/postcss/commit/85c4d7dab830be366f8a96047f9e5b7944e101d8"><code>85c4d7d</code></a>
Another try to fix coverage</li>
<li><a
href="https://github.com/postcss/postcss/commit/94484cae6d4308167939f2ac888d166bd80dff01"><code>94484ca</code></a>
Try to fix coverage</li>
<li><a
href="https://github.com/postcss/postcss/commit/c64b7488d2731dfa16213739b42c34faf5a9eba3"><code>c64b748</code></a>
Load only .map source maps</li>
<li><a
href="https://github.com/postcss/postcss/commit/aaec7b78b3ce2792585b4b300ef1bd5dd5b3e8ad"><code>aaec7b7</code></a>
Avoid throwing JSON parsing errors for non-JSON source maps</li>
<li><a
href="https://github.com/postcss/postcss/commit/233fb264ea4c37f9e2d7b64b2726e6d23fd02327"><code>233fb26</code></a>
Mention original author of the solution</li>
<li>See full diff in <a
href="https://github.com/postcss/postcss/compare/8.5.11...8.5.12">compare
view</a></li>
</ul>
</details>
<br />


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package.json

@@ -137,7 +137,7 @@
     "i18next-cli": "^1.53.2",
     "istanbul": "^0.4.5",
     "istanbul-lib-coverage": "^3.2.2",
-    "postcss": "^8.5.11",
+    "postcss": "^8.5.12",
     "react-hot-loader": "^4.13.1",
     "sass": "^1.99.0",
     "stylelint": "^17.9.1",