chore(deps): update opis/json-schema requirement from 2.4.1 to 2.6.0 in /tools/src/test/php (#707)

Updates the requirements on
[opis/json-schema](https://github.com/opis/json-schema) to permit the
latest version.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/opis/json-schema/releases">opis/json-schema's
releases</a>.</em></p>
<blockquote>
<h2>v2.6.0</h2>
<ul>
<li>improved string length calculation</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/opis/json-schema/commit/8458763e0dd0b6baa310e04f1829fc73da4e8c8a"><code>8458763</code></a>
Improved string length calculation (<a
href="https://redirect.github.com/opis/json-schema/issues/158">#158</a>)</li>
<li><a
href="https://github.com/opis/json-schema/commit/1c59bfd514856a98c01ad0c121f6b915576f9198"><code>1c59bfd</code></a>
PHP 8.5 compatibility (<a
href="https://redirect.github.com/opis/json-schema/issues/156">#156</a>)</li>
<li><a
href="https://github.com/opis/json-schema/commit/b20e989dce3a7d25e477236fe81d11bf31d47599"><code>b20e989</code></a>
Updated AbstractTest.php</li>
<li>See full diff in <a
href="https://github.com/opis/json-schema/compare/2.4.1...2.6.0">compare
view</a></li>
</ul>
</details>
<br />


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</details>

Author: jkowalleck

tools/src/test/php/composer.json

@@ -5,7 +5,7 @@
     "ext-dom": "*",
     "ext-json": "*",
     "ext-libxml": "*",
-    "opis/json-schema": "2.4.1"
+    "opis/json-schema": "2.6.0"
   },
   "require-dev": {
     "roave/security-advisories": "dev-latest"