Auto merge of #27630 - servo:dependabot/cargo/indexmap-1.6.0, r=jdm

Bump indexmap from 1.5.0 to 1.6.0

Bumps [indexmap](https://github.com/bluss/indexmap) from 1.5.0 to 1.6.0.
<details>
<summary>Commits</summary>
<ul>
<li><a href="008e543d9a"><code>008e543</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/bluss/indexmap/issues/152">#152</a> from mbrubeck/deps</li>
<li><a href="083f5a762c"><code>083f5a7</code></a> Version 1.6.0</li>
<li><a href="b0006936b1"><code>b000693</code></a> Update to hashbrown 0.9</li>
<li><a href="e53a6c0317"><code>e53a6c0</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/bluss/indexmap/issues/145">#145</a> from cuviper/explicit-std</li>
<li><a href="4de0dcf4b4"><code>4de0dcf</code></a> Release 1.5.2</li>
<li><a href="ef0adaf4b4"><code>ef0adaf</code></a> Add a feature to explicitly enable &quot;std&quot;</li>
<li><a href="132814cc9c"><code>132814c</code></a> Set 2018 edition in .rustfmt.toml</li>
<li><a href="622dd20631"><code>622dd20</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/bluss/indexmap/issues/149">#149</a> from cuviper/test-chaining</li>
<li><a href="123a35112f"><code>123a351</code></a> ci: make sure test commands are <code>&amp;&amp;</code>-chained</li>
<li><a href="351f6adb2f"><code>351f6ad</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/bluss/indexmap/issues/146">#146</a> from cuviper/release-1.5.1</li>
<li>Additional commits viewable in <a href="https://github.com/bluss/indexmap/compare/1.5.0...1.6.0">compare view</a></li>
</ul>
</details>
<br />

[![Dependabot compatibility score](https://api.dependabot.com/badges/compatibility_score?dependency-name=indexmap&package-manager=cargo&previous-version=1.5.0&new-version=1.6.0)](https://dependabot.com/compatibility-score/?dependency-name=indexmap&package-manager=cargo&previous-version=1.5.0&new-version=1.6.0)

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

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Cargo.lock

@@ -2531,12 +2531,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.8.2"
+version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e91b62f79061a0bc2e046024cb7ba44b08419ed238ecbd9adbd787434b9e8c25"
-dependencies = [
- "autocfg",
-]
+checksum = "00d63df3d41950fb462ed38308eea019113ad1508da725bbedcd0fa5a85ef5f7"
 
 [[package]]
 name = "hashglobe"
@@ -2786,9 +2783,9 @@ dependencies = [
 
 [[package]]
 name = "indexmap"
-version = "1.5.0"
+version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b88cd59ee5f71fea89a62248fc8f387d44400cefe05ef548466d61ced9029a7"
+checksum = "55e2e4c765aa53a0424761bf9f41aa7a6ac1efa87238f59560640e27fca028f2"
 dependencies = [
  "autocfg",
  "hashbrown",