Bump syn from 2.0.3 to 2.0.8 (#2728)

Bumps [syn](https://github.com/dtolnay/syn) from 2.0.3 to 2.0.8.
<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>2.0.8</h2>
<ul>
<li>Treat <code>try</code> keyword as 2015-edition identifier in definition of try macro (<a href="https://redirect.github.com/dtolnay/syn/issues/1422">#1422</a>)</li>
</ul>
<h2>2.0.7</h2>
<ul>
<li>Fix parsing of <code>mut self</code> inside of Type::BareFn</li>
</ul>
<h2>2.0.6</h2>
<ul>
<li>Improve error message on missing ';' between statements (<a href="https://redirect.github.com/dtolnay/syn/issues/1419">#1419</a>)</li>
<li>Keep non-brace macro invocations in trailing expr position as Expr::Macro (<a href="https://redirect.github.com/dtolnay/syn/issues/1420">#1420</a>)</li>
</ul>
<h2>2.0.5</h2>
<ul>
<li>Expose <code>ExprMacro</code> data structure even when <code>features=&quot;full&quot;</code> is not used (<a href="https://redirect.github.com/dtolnay/syn/issues/1417">#1417</a>)</li>
</ul>
<h2>2.0.4</h2>
<ul>
<li>Improve error reporting when parsing identifiers and paths (<a href="https://redirect.github.com/dtolnay/syn/issues/1415">#1415</a>, <a href="https://redirect.github.com/dtolnay/syn/issues/1416">#1416</a>)</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/dtolnay/syn/commit/2fea56f57a1cd5fed439486924f851409e86561f"><code>2fea56f</code></a> Release 2.0.8</li>
<li><a href="https://github.com/dtolnay/syn/commit/40aa291011e191962fc08ba88e753c58d42f5497"><code>40aa291</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/syn/issues/1422">#1422</a> from dtolnay/trymacro</li>
<li><a href="https://github.com/dtolnay/syn/commit/f3a4a4c0c104866ab12619638ba7db4b26d202ad"><code>f3a4a4c</code></a> Treat try keyword as 2015 ident in definition of try macro</li>
<li><a href="https://github.com/dtolnay/syn/commit/b862eff8aa093dda6b8f8cc44418fa789b05b34c"><code>b862eff</code></a> Release 2.0.7</li>
<li><a href="https://github.com/dtolnay/syn/commit/e6b1bdfc2925e0c90e44bfe9f50c9edd24916490"><code>e6b1bdf</code></a> Disallow consecutive path separator in use paths</li>
<li><a href="https://github.com/dtolnay/syn/commit/8ae37b75d6c66f0b794dcc39db0a930200c18e79"><code>8ae37b7</code></a> Fix duplicated name of mut self bare fn arg</li>
<li><a href="https://github.com/dtolnay/syn/commit/78401020bad8455aa415b586fb3c9429c5045c7e"><code>7840102</code></a> Release 2.0.6</li>
<li><a href="https://github.com/dtolnay/syn/commit/e76d6441fd62ec258026c3b5e877e3c4afa5aaf7"><code>e76d644</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/syn/issues/1420">#1420</a> from dtolnay/nonbracemacro</li>
<li><a href="https://github.com/dtolnay/syn/commit/6dcc48070fe72764d1d708db5c16c9e77dc8eeb9"><code>6dcc480</code></a> Keep non-brace macro invocations in trailing expr position as Expr::Macro</li>
<li><a href="https://github.com/dtolnay/syn/commit/d12db40c494530f21c030b9e49d1cfcd1d71e241"><code>d12db40</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/syn/issues/1419">#1419</a> from dtolnay/expectedsemi</li>
<li>Additional commits viewable in <a href="https://github.com/dtolnay/syn/compare/2.0.3...2.0.8">compare view</a></li>
</ul>
</details>
<br />


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</details>

boa_macros/Cargo.toml

@@ -14,6 +14,6 @@ proc-macro = true
 
 [dependencies]
 quote = "1.0.26"
-syn = { version = "2.0.3", features = ["full"] }
+syn = { version = "2.0.8", features = ["full"] }
 proc-macro2 = "1.0"
 synstructure = "0.12"