build(deps): bump cachix/install-nix-action from 18 to 19 (#161)

Bumps [cachix/install-nix-action](https://github.com/cachix/install-nix-action) from 18 to 19.
<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>install-nix-action-v19</h2>
<ul>
<li>expose github_access_token option and use the default github token by default to prevent rate limiting</li>
<li>support <code>--no-daemon</code> installation</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/cachix/install-nix-action/commit/5c11eae19dba042788936d4f1c9685fdd814ac49"><code>5c11eae</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/cachix/install-nix-action/issues/158">#158</a> from cachix/fix-test</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/846213dc1f13fb2f1812c8be1d854b79948bde5a"><code>846213d</code></a> update tests</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/bd6084e16e55fded4460410222ed3c1a7fcd36c1"><code>bd6084e</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/cachix/install-nix-action/issues/156">#156</a> from InternetUnexplorer/update-readme</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/67388ca69eb5c94b15ffe79e08548ff5313663ef"><code>67388ca</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/cachix/install-nix-action/issues/157">#157</a> from zimbatm/default-token</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/a4b8aaf5a24260b643f571235829e53e6b3cc920"><code>a4b8aaf</code></a> Fix rate-limits by using github.token by default</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/70980f045d23efcfcac6fc398474b5d62ee1e8c7"><code>70980f0</code></a> clarify behavior of github_access_token option</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/25d64bbf11b34ad6443b4169002d4a1b163a4b02"><code>25d64bb</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/cachix/install-nix-action/issues/153">#153</a> from InternetUnexplorer/master</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/b95f68250363e6996e0fdafe18cf23c3fc9f873b"><code>b95f682</code></a> fix typo in github_access_token option</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/b15708fdde325ea83010e769b2204dd8fd7e8db7"><code>b15708f</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/cachix/install-nix-action/issues/152">#152</a> from zimbatm/github-access-token</li>
<li><a href="https://github.com/cachix/install-nix-action/commit/c04fcbc1790b0d7beebb69ed234fc4d8bdcac953"><code>c04fcbc</code></a> add github_access_token option</li>
<li>Additional commits viewable in <a href="https://github.com/cachix/install-nix-action/compare/v18...v19">compare view</a></li>
</ul>
</details>
<br />


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</details>

Author: mergify[bot]

.github/workflows/ci.yaml

@@ -39,7 +39,7 @@ jobs:
           echo ::set-output name=short::$(git rev-parse --short HEAD)
 
       - name: Install nix
-        uses: cachix/install-nix-action@v18
+        uses: cachix/install-nix-action@v19
         with:
           nix_path: nixpkgs=channel:nixos-unstable