chore(deps): Bump syn from 2.0.26 to 2.0.27 (#18042)

Bumps [syn](https://github.com/dtolnay/syn) from 2.0.26 to 2.0.27.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/dtolnay/syn/releases">syn's
releases</a>.</em></p>
<blockquote>
<h2>2.0.27</h2>
<ul>
<li>Documentation improvements (thanks <a
href="https://github.com/GuillaumeGomez"><code>@​GuillaumeGomez</code></a>)</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/dtolnay/syn/commit/bb234930b06baf71d88335ff3493d681741c01b6"><code>bb23493</code></a>
Release 2.0.27</li>
<li><a
href="https://github.com/dtolnay/syn/commit/e3a15a911bbffb6b6af3ab375e53e0fccd3fa3e5"><code>e3a15a9</code></a>
Opt in to generate-link-to-definition when building on docs.rs</li>
<li><a
href="https://github.com/dtolnay/syn/commit/36a743af78c2930453375c50f84397b781396188"><code>36a743a</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1490">#1490</a>
from dtolnay/docinline</li>
<li><a
href="https://github.com/dtolnay/syn/commit/535246e7f09f4f1e792469e0af9e37e25bd40e51"><code>535246e</code></a>
Fix useless re-exports section appearing in documentation at crate
root</li>
<li><a
href="https://github.com/dtolnay/syn/commit/3b42902942ecc7dfb6c7427f553079a39e03dc63"><code>3b42902</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1489">#1489</a>
from GuillaumeGomez/unneeded-cfg</li>
<li><a
href="https://github.com/dtolnay/syn/commit/16da0b226f3a7758c0cb850d13691f6b9110d54d"><code>16da0b2</code></a>
Update test suite to nightly-2023-07-21</li>
<li><a
href="https://github.com/dtolnay/syn/commit/268a017becaa22c0d8f6f1cb557cbe511ed84fd0"><code>268a017</code></a>
Remove unneeded cfg</li>
<li><a
href="https://github.com/dtolnay/syn/commit/82c969e548d9e6192a16fdc508df33f7a7722000"><code>82c969e</code></a>
Ignore needless_pass_by_ref_mut clippy lint in generated traits</li>
<li><a
href="https://github.com/dtolnay/syn/commit/517f0e986c64b9ad0c2feaed5ae54a0c8d812c6f"><code>517f0e9</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1487">#1487</a>
from dtolnay/clonefrom</li>
<li><a
href="https://github.com/dtolnay/syn/commit/2cb7f280149c11e6bb921c8326aa8c3ec84b0979"><code>2cb7f28</code></a>
Preserve existing allocations when cloning Punctuated</li>
<li>Additional commits viewable in <a
href="https://github.com/dtolnay/syn/compare/2.0.26...2.0.27">compare
view</a></li>
</ul>
</details>
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