Update pygments to 2.19.0

For our upcoming PEP, we want to use JSON5 code blocks, which was added to pygments in 2.19.

Co-authored-by: Michał Górny <mgorny@quansight.com>

Author: mgorny

requirements.txt

@@ -1,5 +1,5 @@
 # Requirements for building PEPs with Sphinx
-Pygments >= 2.9.0
+Pygments >= 2.19.0
 # Sphinx 6.1.0 broke copying images in parallel builds; fixed in 6.1.2
 # See https://github.com/sphinx-doc/sphinx/pull/11100
 Sphinx >= 5.1.1, != 6.1.0, != 6.1.1, < 8.1.0