chore(deps-dev): bump ts-jest from 26.5.4 to 26.5.6 (#312)

Bumps [ts-jest](https://github.com/kulshekhar/ts-jest) from 26.5.4 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>
<h2><a href="https://github.com/kulshekhar/ts-jest/compare/v26.5.4...v26.5.5">26.5.5</a> (2021-04-15)</h2>
<h3>Bug Fixes</h3>
<ul>
<li><strong>compiler:</strong> return file content on emitSkipped for non ts/tsx files (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2515">#2515</a>) (<a href="https://github.com/kulshekhar/ts-jest/commit/0320fb3ac22056aafe4d7ae966eab84dbf23fda9">0320fb3</a>), closes <a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2513">#2513</a></li>
</ul>
<h1><a href="https://github.com/kulshekhar/ts-jest/compare/v27.0.0-next.10...v27.0.0-next.11">27.0.0-next.11</a> (2021-04-15)</h1>
<h3>Bug Fixes</h3>
<ul>
<li><strong>compiler:</strong> return file content on emitSkipped for non ts/tsx files (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2519">#2519</a>) (<a href="https://github.com/kulshekhar/ts-jest/commit/a4e5640f54a7810c9b7aba32663ce4a53893d22f">a4e5640</a>), closes <a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2513">#2513</a></li>
</ul>
<h3>Features</h3>
<ul>
<li>support jest <strong>27.0.0-next.7</strong> (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2498">#2498</a>) (<a href="https://github.com/kulshekhar/ts-jest/commit/a10af91e2c3128c8de732a421f743621e60dbe8e">a10af91</a>)</li>
<li>support jest <strong>27.0.0-next.8</strong> (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2512">#2512</a>) (<a href="https://github.com/kulshekhar/ts-jest/commit/999ef60c93801de5cdb1a3483af16090e3a1b52e">999ef60</a>)</li>
</ul>
<h1><a href="https://github.com/kulshekhar/ts-jest/compare/v27.0.0-next.9...v27.0.0-next.10">27.0.0-next.10</a> (2021-03-30)</h1>
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</blockquote>
<p>... (truncated)</p>
</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><a href="https://github.com/kulshekhar/ts-jest/commit/e448638964b015c1ccf3e3de336b8dafee8f4a1c"><code>e448638</code></a> chore(release): 26.5.5</li>
<li><a href="https://github.com/kulshekhar/ts-jest/commit/3e9a9f7005c7930b3a7eca0922763052fb3d5c88"><code>3e9a9f7</code></a> refactor(compiler): improve error message for emit skipped (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2518">#2518</a>)</li>
<li><a href="https://github.com/kulshekhar/ts-jest/commit/0320fb3ac22056aafe4d7ae966eab84dbf23fda9"><code>0320fb3</code></a> fix(compiler): return file content on emitSkipped for non ts/tsx files (<a href="https://github-redirect.dependabot.com/kulshekhar/ts-jest/issues/2515">#2515</a>)</li>
<li>See full diff in <a href="https://github.com/kulshekhar/ts-jest/compare/v26.5.4...v26.5.6">compare view</a></li>
</ul>
</details>
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