⬆️ Update pygments requirement from <2.19 to <2.20 (#1014)

* ⬆️ Update pygments requirement from <2.19 to <2.20

Updates the requirements on [pygments](https://github.com/pygments/pygments) to permit the latest version.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@0.5...2.19.1)

---
updated-dependencies:
- dependency-name: pygments
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

* update

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Chris Sewell <chrisj_sewell@hotmail.com>

Author: dependabot[bot]

pyproject.toml

@@ -74,7 +74,7 @@ testing = [
     "pytest-regressions",
     "pytest-param-files~=0.6.0",
     "sphinx-pytest",
-    "pygments<2.19",  # TODO fix test regression with 2.19"
+    "pygments<2.20",  # TODO fix test regression with 2.19"
 ]
 testing-docutils = [
     "pygments",

tests/test_sphinx/test_sphinx_builds/test_includes.html

@@ -115,7 +115,7 @@ <h2>
 </pre>
       </div>
      </div>
-     <pre class="code python literal-block"><small class="ln">0 </small><code data-lineno="0 "><span class="keyword">def</span> <span class="name function">a_func</span><span class="punctuation">(</span><span class="name">param</span><span class="punctuation">):</span><span class="whitespace">
+     <pre class="code python literal-block"><small class="ln">0 </small><code data-lineno="0 "><span class="keyword">def</span><span class="whitespace"> </span><span class="name function">a_func</span><span class="punctuation">(</span><span class="name">param</span><span class="punctuation">):</span><span class="whitespace">
 </span></code><small class="ln">1 </small><code data-lineno="1 "><span class="whitespace"></span>    <span class="name builtin">print</span><span class="punctuation">(</span><span class="name">param</span><span class="punctuation">)</span></code></pre>
      <div class="highlight-default notranslate">
       <div class="highlight">

tests/test_sphinx/test_sphinx_builds/test_includes.xml

@@ -53,6 +53,7 @@
             <literal_block classes="code python" source="include_code.py" xml:space="preserve">
                 <inline classes="keyword">
                     def
+                <inline classes="whitespace">
 
                 <inline classes="name function">
                     a_func
@@ -78,6 +79,7 @@
                     0
                 <inline classes="keyword">
                     def
+                <inline classes="whitespace">
 
                 <inline classes="name function">
                     a_func