build(deps): Bump github.com/prometheus/client_golang from 1.8.0 to 1.9.0 (#5807)

Bumps [github.com/prometheus/client_golang](https://github.com/prometheus/client_golang) from 1.8.0 to 1.9.0.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/prometheus/client_golang/releases">github.com/prometheus/client_golang's releases</a>.</em></p>
<blockquote>
<h2>1.9.0 / 2020-12-17</h2>
<ul>
<li>[FEATURE] <code>NewPidFileFn</code> helper to create process collectors for processes whose PID is read from a file. <a href="https://github-redirect.dependabot.com/prometheus/client_golang/issues/804">#804</a></li>
<li>[BUGFIX] promhttp: Prevent endless loop in <code>InstrumentHandler...</code> middlewares with invalid metric or label names. <a href="https://github-redirect.dependabot.com/prometheus/client_golang/issues/823">#823</a></li>
</ul>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/prometheus/client_golang/blob/master/CHANGELOG.md">github.com/prometheus/client_golang's changelog</a>.</em></p>
<blockquote>
<h2>1.9.0 / 2020-12-17</h2>
<ul>
<li>[FEATURE] <code>NewPidFileFn</code> helper to create process collectors for processes whose PID is read from a file. <a href="https://github-redirect.dependabot.com/prometheus/client_golang/issues/804">#804</a></li>
<li>[BUGFIX] promhttp: Prevent endless loop in <code>InstrumentHandler...</code> middlewares with invalid metric or label names. <a href="https://github-redirect.dependabot.com/prometheus/client_golang/issues/823">#823</a></li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/prometheus/client_golang/commit/d89cf5af8849fcb6d69f2c16bdf3b910e03d341e"><code>d89cf5a</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/prometheus/client_golang/issues/826">#826</a> from prometheus/beorn7/release</li>
<li><a href="https://github.com/prometheus/client_golang/commit/80ca9cdc4e154cf193f8b1b8fddb1f24a3bcc475"><code>80ca9cd</code></a> Cut release 1.9.0</li>
<li><a href="https://github.com/prometheus/client_golang/commit/8d16199dea38f0d689454d6e56ffaeb1d381f6bb"><code>8d16199</code></a> Update dependencies</li>
<li><a href="https://github.com/prometheus/client_golang/commit/8b73bd904c6b7929b7dcaefea4fbcc9c7a439449"><code>8b73bd9</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/prometheus/client_golang/issues/823">#823</a> from prometheus/beorn7/promhttp</li>
<li><a href="https://github.com/prometheus/client_golang/commit/98eb6cbf7ccf0487b869d70efeebbb09dab53be1"><code>98eb6cb</code></a> promhttp: Correctly detect invalid metric and label names</li>
<li><a href="https://github.com/prometheus/client_golang/commit/37c26edd5bccddcf5d0622534fcdc36c301d89d6"><code>37c26ed</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/prometheus/client_golang/issues/821">#821</a> from prometheus/beorn7/multierror</li>
<li><a href="https://github.com/prometheus/client_golang/commit/34ca1203775369991cf963e1b71fe1f230064dc5"><code>34ca120</code></a> Be more explicit about the multi-line properties of MultiError</li>
<li><a href="https://github.com/prometheus/client_golang/commit/fd6d36867616fa5606efb2788d3368768923ff7b"><code>fd6d368</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/prometheus/client_golang/issues/819">#819</a> from jubalh/sp</li>
<li><a href="https://github.com/prometheus/client_golang/commit/cf6dc827807a19a925656652203f34a788f1c035"><code>cf6dc82</code></a> Correct spelling: possibilites -&gt; possibilities</li>
<li><a href="https://github.com/prometheus/client_golang/commit/39b478e90c0bbd869817725d4553687513b7cf01"><code>39b478e</code></a> Added example api code showing how to add auth tokens and user agents to prom...</li>
<li>Additional commits viewable in <a href="https://github.com/prometheus/client_golang/compare/v1.8.0...v1.9.0">compare view</a></li>
</ul>
</details>
<br />


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</details>

go.mod

@@ -21,7 +21,7 @@ require (
 	github.com/libp2p/go-buffer-pool v0.0.2
 	github.com/minio/highwayhash v1.0.1
 	github.com/pkg/errors v0.9.1
-	github.com/prometheus/client_golang v1.8.0
+	github.com/prometheus/client_golang v1.9.0
 	github.com/rcrowley/go-metrics v0.0.0-20200313005456-10cdbea86bc0
 	github.com/rs/cors v1.7.0
 	github.com/sasha-s/go-deadlock v0.2.0