build(deps-dev): Bump ts-jest from 26.5.5 to 26.5.6 (#328)

Bumps [ts-jest](https://github.com/kulshekhar/ts-jest) from 26.5.5 to 26.5.6.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/kulshekhar/ts-jest/blob/master/CHANGELOG.md">ts-jest's changelog</a>.</em></p>
<blockquote>
<h2><a href="https://github.com/kulshekhar/ts-jest/compare/v26.5.5...v26.5.6">26.5.6</a> (2021-05-05)</h2>
<h3>Code Refactoring</h3>
<ul>
<li>refactor(config): show warning message for <code>sourceMap: false</code> (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/pull/2557">#2557</a>) (<a href="https://github.com/kulshekhar/ts-jest/commit/cf609900e2c5937755123bd08ca2c5f2ff5e0651">cf60990</a>).</li>
</ul>
<h1><a href="https://github.com/kulshekhar/ts-jest/compare/v27.0.0-next.11...v27.0.0-next.12">27.0.0-next.12</a> (2021-05-05)</h1>
<h3>Features</h3>
<ul>
<li><strong>config:</strong> allow disable sourcemap (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2544">#2544</a>) (<a href="https://github.com/kulshekhar/ts-jest/commit/47da6ada5089e58e9bc68ce8e9bc9e17aaa127ae">47da6ad</a>)</li>
</ul>
<h2>BREAKING CHANGES</h2>
<ul>
<li>By default, <code>ts-jest</code> will use <code>sourceMap</code> option from your <code>tsconfig</code>. If users want to have sourcemap on, they need to either remove <code>sourceMap</code> or set <code>sourceMap: true</code> in <code>tsconfig</code></li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/kulshekhar/ts-jest/commit/46bf72d8bac9a9eccfdb61d96862242bf2ea5dd7"><code>46bf72d</code></a> chore(release): 26.5.6 (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2559">#2559</a>)</li>
<li><a href="https://github.com/kulshekhar/ts-jest/commit/cf609900e2c5937755123bd08ca2c5f2ff5e0651"><code>cf60990</code></a> refactor(config): show warning message for <code>sourceMap: false</code> (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2557">#2557</a>)</li>
<li>See full diff in <a href="https://github.com/kulshekhar/ts-jest/compare/v26.5.5...v26.5.6">compare view</a></li>
</ul>
</details>
<br />


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</details>

yarn.lock

@@ -5734,9 +5734,9 @@ trim-off-newlines@^1.0.0:
   integrity sha1-n5up2e+odkw4dpi8v+sshI8RrbM=
 
 ts-jest@^26.1.0:
-  version "26.5.5"
-  resolved "https://registry.yarnpkg.com/ts-jest/-/ts-jest-26.5.5.tgz#e40481b6ee4dd162626ba481a2be05fa57160ea5"
-  integrity sha512-7tP4m+silwt1NHqzNRAPjW1BswnAhopTdc2K3HEkRZjF0ZG2F/e/ypVH0xiZIMfItFtD3CX0XFbwPzp9fIEUVg==
+  version "26.5.6"
+  resolved "https://registry.yarnpkg.com/ts-jest/-/ts-jest-26.5.6.tgz#c32e0746425274e1dfe333f43cd3c800e014ec35"
+  integrity sha512-rua+rCP8DxpA8b4DQD/6X2HQS8Zy/xzViVYfEs2OQu68tkCuKLV0Md8pmX55+W24uRIyAsf/BajRfxOs+R2MKA==
   dependencies:
     bs-logger "0.x"
     buffer-from "1.x"