Bump syn from 2.0.61 to 2.0.63 (#2390)

Bumps [syn](https://github.com/dtolnay/syn) from 2.0.61 to 2.0.63.
<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>2.0.63</h2>
<ul>
<li>Parse and print long if-else-if chains without reliance on deep
recursion to avoid overflowing stack (<a
href="https://redirect.github.com/dtolnay/syn/issues/1644">#1644</a>, <a
href="https://redirect.github.com/dtolnay/syn/issues/1645">#1645</a>)</li>
</ul>
<h2>2.0.62</h2>
<ul>
<li>Reject invalid unparenthesized range and comparison operator
expressions (<a
href="https://redirect.github.com/dtolnay/syn/issues/1642">#1642</a>, <a
href="https://redirect.github.com/dtolnay/syn/issues/1643">#1643</a>)</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/dtolnay/syn/commit/8bcd277e4c277a8a64542287e9dd232bc27c3328"><code>8bcd277</code></a>
Release 2.0.63</li>
<li><a
href="https://github.com/dtolnay/syn/commit/6d1113df339f6e6fc87d16e56e3e0c5626a37a19"><code>6d1113d</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1645">#1645</a>
from dtolnay/ifelse</li>
<li><a
href="https://github.com/dtolnay/syn/commit/40950ddb27ff5fcfdf64dc9a4fa9fc98fd98d267"><code>40950dd</code></a>
Remove recursion from printing of Expr::If</li>
<li><a
href="https://github.com/dtolnay/syn/commit/e2e7f2dd2261e35c5e3f3f41296995471516531a"><code>e2e7f2d</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1644">#1644</a>
from dtolnay/ifelse</li>
<li><a
href="https://github.com/dtolnay/syn/commit/70777ceec1b085527392d64ebf3d9f43803187ae"><code>70777ce</code></a>
Remove recursion from parsing of Expr::If</li>
<li><a
href="https://github.com/dtolnay/syn/commit/e9e6329cf8b388b5323c3f2c926561687d38927e"><code>e9e6329</code></a>
Release 2.0.62</li>
<li><a
href="https://github.com/dtolnay/syn/commit/c79cea17721eaeec2d7ef6c9624993de9613ea26"><code>c79cea1</code></a>
Merge pull request <a
href="https://redirect.github.com/dtolnay/syn/issues/1643">#1643</a>
from dtolnay/chainedcompare</li>
<li><a
href="https://github.com/dtolnay/syn/commit/dc4ffde94ecac024785fd4fe75e7318fbc46be22"><code>dc4ffde</code></a>
Require parens for chained comparison binops</li>
<li><a
href="https://github.com/dtolnay/syn/commit/c463a74f7bd4f8cd81a57c8a77faece2d2590a42"><code>c463a74</code></a>
Add tests of binop associativity</li>
<li><a
href="https://github.com/dtolnay/syn/commit/da509d51edddf790154133ed2a57f1fcc7387c88"><code>da509d5</code></a>
Add test of assignment and range precedence</li>
<li>Additional commits viewable in <a
href="https://github.com/dtolnay/syn/compare/2.0.61...2.0.63">compare
view</a></li>
</ul>
</details>
<br />


[![Dependabot compatibility
score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=syn&package-manager=cargo&previous-version=2.0.61&new-version=2.0.63)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

Dependabot will resolve any conflicts with this PR as long as you don't
alter it yourself. You can also trigger a rebase manually by commenting
`@dependabot rebase`.

[//]: # (dependabot-automerge-start)
[//]: # (dependabot-automerge-end)

---

<details>
<summary>Dependabot commands and options</summary>
<br />

You can trigger Dependabot actions by commenting on this PR:
- `@dependabot rebase` will rebase this PR
- `@dependabot recreate` will recreate this PR, overwriting any edits
that have been made to it
- `@dependabot merge` will merge this PR after your CI passes on it
- `@dependabot squash and merge` will squash and merge this PR after
your CI passes on it
- `@dependabot cancel merge` will cancel a previously requested merge
and block automerging
- `@dependabot reopen` will reopen this PR if it is closed
- `@dependabot close` will close this PR and stop Dependabot recreating
it. You can achieve the same result by closing it manually
- `@dependabot show <dependency name> ignore conditions` will show all
of the ignore conditions of the specified dependency
- `@dependabot ignore this major version` will close this PR and stop
Dependabot creating any more for this major version (unless you reopen
the PR or upgrade to it yourself)
- `@dependabot ignore this minor version` will close this PR and stop
Dependabot creating any more for this minor version (unless you reopen
the PR or upgrade to it yourself)
- `@dependabot ignore this dependency` will close this PR and stop
Dependabot creating any more for this dependency (unless you reopen the
PR or upgrade to it yourself)


</details>

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>