Bump github.com/sanity-io/litter from 1.5.2 to 1.5.8 (#5451)

Bumps [github.com/sanity-io/litter](https://github.com/sanity-io/litter)
from 1.5.2 to 1.5.8.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/sanity-io/litter/commit/4fde30cab354d1dc18c21d2a1b9ac5c75600ec19"><code>4fde30c</code></a>
fix: fixes panic on unexported field access.</li>
<li><a
href="https://github.com/sanity-io/litter/commit/61ca8aa20ab3dd224ead03cb8e89e9ba38ad5116"><code>61ca8aa</code></a>
feat: support <code>FormatTime</code>.</li>
<li><a
href="https://github.com/sanity-io/litter/commit/3d1485f1f260405aa7f9b4f7e573c3d4809ec302"><code>3d1485f</code></a>
chore: fix deprecations.</li>
<li><a
href="https://github.com/sanity-io/litter/commit/7e132579048ac450c3cbcd4d448efbae937017e1"><code>7e13257</code></a>
feat: adds <code>D()</code>, a shorthand for <code>Dump()</code>.</li>
<li><a
href="https://github.com/sanity-io/litter/commit/f2ba02b77978d2fb5030483056f1939027fd1abc"><code>f2ba02b</code></a>
fix: don't cache array/slice length when traversing.</li>
<li><a
href="https://github.com/sanity-io/litter/commit/c028d3cb966dda224fc5c54dda5b246b478fe149"><code>c028d3c</code></a>
ci: adds GitHub Actions action.</li>
<li><a
href="https://github.com/sanity-io/litter/commit/cfce9160a04515cc54f0b6fb4c0e2eb1c6edf590"><code>cfce916</code></a>
Fix pointer resued in maps key</li>
<li><a
href="https://github.com/sanity-io/litter/commit/65e672ecd4d7f12e1e7da5ca7185ffea6cc8ac9f"><code>65e672e</code></a>
ci: removes .travis.yml, which is no longer operative</li>
<li>See full diff in <a
href="https://github.com/sanity-io/litter/compare/v1.5.2...v1.5.8">compare
view</a></li>
</ul>
</details>
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