chore(deps): bump pygments from 2.16.1 to 2.20.0 in /.kokoro

Bumps [pygments](https://github.com/pygments/pygments) from 2.16.1 to 2.20.0.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.16.1...2.20.0)

---
updated-dependencies:
- dependency-name: pygments
  dependency-version: 2.20.0
  dependency-type: indirect
...

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

Author: dependabot[bot]

.kokoro/requirements.txt

@@ -429,9 +429,9 @@ pycparser==2.21 \
     --hash=sha256:8ee45429555515e1f6b185e78100aea234072576aa43ab53aefcae078162fca9 \
     --hash=sha256:e644fdec12f7872f86c58ff790da456218b10f863970249516d60a5eaca77206
     # via cffi
-pygments==2.16.1 \
-    --hash=sha256:13fc09fa63bc8d8671a6d247e1eb303c4b343eaee81d861f3404db2935653692 \
-    --hash=sha256:1daff0494820c69bc8941e407aa20f577374ee88364ee10a98fdbe0aece96e29
+pygments==2.20.0 \
+    --hash=sha256:6757cd03768053ff99f3039c1a36d6c0aa0b263438fcab17520b30a303a82b5f \
+    --hash=sha256:81a9e26dd42fd28a23a2d169d86d7ac03b46e2f8b59ed4698fb4785f946d0176
     # via
     #   readme-renderer
     #   rich