chore: Bump golang.org/x/sync from 0.14.0 to 0.15.0 (#400)

Bumps [golang.org/x/sync](https://github.com/golang/sync) from 0.14.0 to
0.15.0.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/golang/sync/commit/8a14946fb031f4bf6096242b5e6ae6f7316d47d8"><code>8a14946</code></a>
errgroup: remove duplicated comment</li>
<li><a
href="https://github.com/golang/sync/commit/1869c690bf11da5dd230e188d03a612a4a3f8ba6"><code>1869c69</code></a>
all: replace deprecated ioutil</li>
<li><a
href="https://github.com/golang/sync/commit/d1ac909e84c04f4326f620436b3894b3f5de0bd4"><code>d1ac909</code></a>
sync/errgroup: PanicError.Error print stack trace</li>
<li>See full diff in <a
href="https://github.com/golang/sync/compare/v0.14.0...v0.15.0">compare
view</a></li>
</ul>
</details>
<br />


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

Author: dependabot[bot]