Bumps [k256](https://github.com/RustCrypto/elliptic-curves) from 0.13.3
to 0.13.4.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/RustCrypto/elliptic-curves/commit/5ac8f5d77f11399ff48d87b0554935f6eddda342"><code>5ac8f5d</code></a>
k256 v0.13.4</li>
<li><a
href="https://github.com/RustCrypto/elliptic-curves/commit/613cbafd63763c579922ad2b79fa041b4a0dde50"><code>613cbaf</code></a>
k256: add support for non-32-byte BIP340 signatures (<a
href="https://redirect.github.com/RustCrypto/elliptic-curves/issues/1041">#1041</a>)</li>
<li><a
href="https://github.com/RustCrypto/elliptic-curves/commit/3787e4cd5b4223cae8bed05d087d6ff2f1d9430b"><code>3787e4c</code></a>
k256 v0.13.3</li>
<li>See full diff in <a
href="https://github.com/RustCrypto/elliptic-curves/compare/k256/v0.13.3...k256/v0.13.4">compare
view</a></li>
</ul>
</details>
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