Pin pygments in CI (Qiskit#9938)

The recent release of pygments 2.15.0 [1] has started emitting an
error in the custom qasm pygments lexer included in qiskit in
OpenQASMLexer. In the interest of not blocking CI this commit pins the
pygments version we're installing in CI. Longer term, we should probably
look at just deprecating the qiskit version and just using
openqasm-pygments which is the pygments tools for OpenQASM maintained by
the openqasm community.

[1] https://pypi.org/project/Pygments/2.15.0/

requirements-dev.txt

@@ -19,7 +19,7 @@ reno>=3.4.0
 Sphinx>=5.0
 qiskit-sphinx-theme>=1.6
 sphinx-design>=0.2.0
-pygments>=2.4
+pygments>=2.4,<2.15
 scikit-learn>=0.20.0
 scikit-quant<=0.7;platform_system != 'Windows'
 jax;platform_system != 'Windows'