chore: Bump golang.org/x/mod from 0.19.0 to 0.20.0 (#5897)

Bumps [golang.org/x/mod](https://github.com/golang/mod) from 0.19.0 to 0.20.0.
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<summary>Commits</summary>
<ul>
<li><a href="https://github.com/golang/mod/commit/bc151c4e8ccc31931553c47d43e41c0efc246096"><code>bc151c4</code></a> README: fix link to x/tools</li>
<li><a href="https://github.com/golang/mod/commit/d1f873e3c1b2cf7231a30697aea158ae6cfdbb5f"><code>d1f873e</code></a> modfile: fix Cleanup clobbering Line reference</li>
<li><a href="https://github.com/golang/mod/commit/b56a28f8bd8379d47ee77b658799ce29061f6abe"><code>b56a28f</code></a> modfile: Add support for tool lines</li>
<li><a href="https://github.com/golang/mod/commit/79169e9d3645b69457c3c546644e29ba620146e7"><code>79169e9</code></a> LICENSE: update per Google Legal</li>
<li>See full diff in <a href="https://github.com/golang/mod/compare/v0.19.0...v0.20.0">compare view</a></li>
</ul>
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