Update pygments requirement from >=2.17,<2.21 to ==2.21.* in the optional group across 1 directory (#10026)

Author: dependabot[bot]

pyproject.toml

@@ -65,7 +65,7 @@ optional = [
   "legacy-cgi; python_version>='3.13'",
   "markdown>=3.3.7",
   "psycopg[binary]>=3.1.8",
-  "pygments>=2.17,<2.21",
+  "pygments==2.21.*",
   "pyyaml>=5.3.1,<6.1",
   "requests",
   "uritemplate",

tests/test_description.py

@@ -41,7 +41,7 @@
 </code></pre>
 <p>indented</p>
 <h2 id="hash-style-header">hash style header</h2>
-<div class="highlight"><pre><span></span><span class="p">[{</span><br /><span class="w">    </span><span class="nt">&quot;alpha&quot;</span><span class="p">:</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><br /><span class="w">    </span><span class="nt">&quot;beta&quot;</span><span class="p">:</span><span class="w"> </span><span class="s2">&quot;this is a string&quot;</span><br /><span class="p">}]</span><br /></pre></div>
+<div class="highlight"><pre><span></span><span class="p">[{</span><br /><span class="w">    </span><span class="nt">"alpha"</span><span class="p">:</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><br /><span class="w">    </span><span class="nt">"beta"</span><span class="p">:</span><span class="w"> </span><span class="s2">"this is a string"</span><br /><span class="p">}]</span><br /></pre></div>
 <p><br /></p>"""