Bump cachix/install-nix-action from 26 to 27 (#456)

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 26 to 27.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/cachix/install-nix-action/releases">cachix/install-nix-action's releases</a>.</em></p>
<blockquote>
<h2>v27</h2>
<h2>What's Changed</h2>
<ul>
<li>Enable <code>always-allow-substitutes</code> by default by <a href="https://github.com/sandydoo"><code>@​sandydoo</code></a> in <a href="https://redirect.github.com/cachix/install-nix-action/pull/207">cachix/install-nix-action#207</a></li>
<li>nix: 2.20.5 -&gt; 2.22.1 by <a href="https://github.com/kashw2"><code>@​kashw2</code></a> in <a href="https://redirect.github.com/cachix/install-nix-action/pull/206">cachix/install-nix-action#206</a></li>
<li>ci: fix tests by <a href="https://github.com/sandydoo"><code>@​sandydoo</code></a> in <a href="https://redirect.github.com/cachix/install-nix-action/pull/208">cachix/install-nix-action#208</a></li>
</ul>
<h2>New Contributors</h2>
<ul>
<li><a href="https://github.com/kashw2"><code>@​kashw2</code></a> made their first contribution in <a href="https://redirect.github.com/cachix/install-nix-action/pull/206">cachix/install-nix-action#206</a></li>
</ul>
<p><strong>Full Changelog</strong>: <a href="https://github.com/cachix/install-nix-action/compare/v26...V27">https://github.com/cachix/install-nix-action/compare/v26...V27</a></p>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/cachix/install-nix-action/commit/ba0dd844c9180cbf77aa72a116d6fbc515d0e87b"><code>ba0dd84</code></a> Merge pull request <a href="https://redirect.github.com/cachix/install-nix-action/issues/208">#208</a> from cachix/fix-macos-tests</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/d9660bf088514a2ede4707708ba35de0a1b69a3d"><code>d9660bf</code></a> ci: updated pinned installer</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/1e14eb01bfd97127cae3cc76eddb538ed44af120"><code>1e14eb0</code></a> Merge pull request <a href="https://redirect.github.com/cachix/install-nix-action/issues/206">#206</a> from kashw2/nix-update</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/6060e02b1f9cb669240905a2db3fa1d327692d44"><code>6060e02</code></a> 2.22.1</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/262815eb715530d99d468e099f9c53a1d7557fda"><code>262815e</code></a> Merge pull request <a href="https://redirect.github.com/cachix/install-nix-action/issues/207">#207</a> from cachix/always-allow-substitutes</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/5dce380a8bcabd02812ffac2471c6a4f5a470c7c"><code>5dce380</code></a> Update README with more installer differences</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/2f469017fc567f1b7fe6d1d7c21021c02ad55105"><code>2f46901</code></a> ci: update nixpkgs channel</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/529d65921746c2b43d8a8a0458544a4a51f6ddc3"><code>529d659</code></a> ci: add aarch64-darwin tests where possible</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/d6c2f5b78803207e177e2f3d3d2d2899df69c6f2"><code>d6c2f5b</code></a> ci: switch to macos-13</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/01dba9f77095b5f03102533169760a81c51f2205"><code>01dba9f</code></a> Update README</li>
<li>Additional commits viewable in <a href="https://github.com/cachix/install-nix-action/compare/v26...V27">compare view</a></li>
</ul>
</details>
<br />


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</details>

.github/workflows/ci.yaml

@@ -23,7 +23,7 @@ jobs:
           fetch-depth: 5
 
       - name: Install nix
-        uses: cachix/install-nix-action@v26
+        uses: cachix/install-nix-action@V27
         with:
           nix_path: nixpkgs=channel:nixpkgs-unstable