build(deps): Bump github.com/cosmos/iavl from 0.15.2 to 0.15.3 (#5814)

Bumps [github.com/cosmos/iavl](https://github.com/cosmos/iavl) from 0.15.2 to 0.15.3.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/cosmos/iavl/releases">github.com/cosmos/iavl's releases</a>.</em></p>
<blockquote>
<h2>v0.15.3</h2>
<p><a href="https://github.com/cosmos/iavl/blob/257e8b9292e784aef5b755d9f8fd305eb1e29bb0/CHANGELOG.md#0153-december-21-2020">https://github.com/cosmos/iavl/blob/257e8b9292e784aef5b755d9f8fd305eb1e29bb0/CHANGELOG.md#0153-december-21-2020</a></p>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/cosmos/iavl/blob/master/CHANGELOG.md">github.com/cosmos/iavl's changelog</a>.</em></p>
<blockquote>
<h2>0.15.3 (December 21, 2020)</h2>
<p>Special thanks to external contributors on this release: <a href="https://github.com/odeke-em">@odeke-em</a></p>
<h3>Improvements</h3>
<ul>
<li><a href="https://github-redirect.dependabot.com/cosmos/iavl/pull/352">#352</a> Reuse buffer to improve performance of <code>GetMembershipProof()</code> and <code>GetNonMembershipProof()</code>.</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/cosmos/iavl/commit/257e8b9292e784aef5b755d9f8fd305eb1e29bb0"><code>257e8b9</code></a> changelog: release 0.15.3 (<a href="https://github-redirect.dependabot.com/cosmos/iavl/issues/353">#353</a>)</li>
<li><a href="https://github.com/cosmos/iavl/commit/b2dffed4b2c76c5dfa7c4bb4683030c9c8d2f022"><code>b2dffed</code></a> convertVarIntToBytes: use reusable bytes array (<a href="https://github-redirect.dependabot.com/cosmos/iavl/issues/352">#352</a>)</li>
<li><a href="https://github.com/cosmos/iavl/commit/9e510e5a64824e1f6aab6a36b9300965251b043b"><code>9e510e5</code></a> github: run tests with 32-bit arch as well (<a href="https://github-redirect.dependabot.com/cosmos/iavl/issues/350">#350</a>)</li>
<li>See full diff in <a href="https://github.com/cosmos/iavl/compare/v0.15.2...v0.15.3">compare view</a></li>
</ul>
</details>
<br />


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</details>

go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/btcsuite/btcd v0.21.0-beta
 	github.com/btcsuite/btcutil v1.0.2
 	github.com/confio/ics23/go v0.6.3
-	github.com/cosmos/iavl v0.15.2
+	github.com/cosmos/iavl v0.15.3
 	github.com/fortytw2/leaktest v1.3.0
 	github.com/go-kit/kit v0.10.0
 	github.com/go-logfmt/logfmt v0.5.0

go.sum

@@ -104,8 +104,8 @@ github.com/cosmos/iavl v0.15.0-rc3.0.20201009144442-230e9bdf52cd h1:K3bmPkMDnd2K
 github.com/cosmos/iavl v0.15.0-rc3.0.20201009144442-230e9bdf52cd/go.mod h1:3xOIaNNX19p0QrX0VqWa6voPRoJRGGYtny+DH8NEPvE=
 github.com/cosmos/iavl v0.15.0-rc5 h1:AMKgaAjXwGANWv56NL4q4hV+a0puSkLYD6cCQAv3i44=
 github.com/cosmos/iavl v0.15.0-rc5/go.mod h1:WqoPL9yPTQ85QBMT45OOUzPxG/U/JcJoN7uMjgxke/I=
-github.com/cosmos/iavl v0.15.2 h1:caJFlSFRCgUDBavRL92JRILI2Lx+7zWxzKGY/CI2qxA=
-github.com/cosmos/iavl v0.15.2/go.mod h1:OLjQiAQ4fGD2KDZooyJG9yz+p2ao2IAYSbke8mVvSA4=
+github.com/cosmos/iavl v0.15.3 h1:xE9r6HW8GeKeoYJN4zefpljZ1oukVScP/7M8oj6SUts=
+github.com/cosmos/iavl v0.15.3/go.mod h1:OLjQiAQ4fGD2KDZooyJG9yz+p2ao2IAYSbke8mVvSA4=
 github.com/cpuguy83/go-md2man v1.0.10/go.mod h1:SmD6nW6nTyfqj6ABTjUi3V3JVMnlJmwcJI5acqYI6dE=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/cpuguy83/go-md2man/v2 v2.0.0/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=