build(deps): Bump syn from 2.0.68 to 2.0.69 (#568)

Bumps [syn](https://github.com/dtolnay/syn) from 2.0.68 to 2.0.69.
<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>2.0.69</h2>
<ul>
<li>Correctly parenthesize labeled loops inside a break value (<a
href="https://redirect.github.com/dtolnay/syn/issues/1692">#1692</a>)</li>
<li>Add <code>Punctuated::get</code> and <code>get_mut</code> (<a
href="https://redirect.github.com/dtolnay/syn/issues/1693">#1693</a>)</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/dtolnay/syn/commit/d4a0ff556fe1bbcaa77ebc37d24cc1bdaf5eac3a"><code>d4a0ff5</code></a>
Release 2.0.69</li>
<li><a
href="https://github.com/dtolnay/syn/commit/0f7213407fb59cca90a1097747868b68b32ff020"><code>0f72134</code></a>
Improve precedence variant name of sum and product operators</li>
<li><a
href="https://github.com/dtolnay/syn/commit/06f34fce1a62e75fbd0400b93181ff989e16505b"><code>06f34fc</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1693">#1693</a>
from dtolnay/get</li>
<li><a
href="https://github.com/dtolnay/syn/commit/a4438571c902aae659ff568419fa4af029b5c0b0"><code>a443857</code></a>
Add Punctuated::get and get_mut</li>
<li><a
href="https://github.com/dtolnay/syn/commit/f0dfdbd9af41fe75ee6054daca545d80a4374a32"><code>f0dfdbd</code></a>
Update test suite to nightly-2024-07-05</li>
<li><a
href="https://github.com/dtolnay/syn/commit/1560f9a2ac7937fee688eaa98ad009caaeef323c"><code>1560f9a</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1692">#1692</a>
from dtolnay/break</li>
<li><a
href="https://github.com/dtolnay/syn/commit/4e71c1caa413122a644f9e3fcb8222dfc20d9f8d"><code>4e71c1c</code></a>
Parenthesize labeled loops inside break value</li>
<li><a
href="https://github.com/dtolnay/syn/commit/93931a4f243665a1e50748072b9fac1adbcebb7c"><code>93931a4</code></a>
Add fixup test for break with leading label</li>
<li><a
href="https://github.com/dtolnay/syn/commit/cc5e64e4143099699c5c7f20791c563e71395455"><code>cc5e64e</code></a>
Update test suite to nightly-2024-06-29</li>
<li><a
href="https://github.com/dtolnay/syn/commit/2bbf612a945f94860be6197c1efc76f8e3ae9e6c"><code>2bbf612</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1691">#1691</a>
from dtolnay/postfix</li>
<li>Additional commits viewable in <a
href="https://github.com/dtolnay/syn/compare/2.0.68...2.0.69">compare
view</a></li>
</ul>
</details>
<br />


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