Bump pygments from 2.15.1 to 2.16.1

Bumps [pygments](https://github.com/pygments/pygments) from 2.15.1 to 2.16.1.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.15.1...2.16.1)

---
updated-dependencies:
- dependency-name: pygments
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements_test.txt

@@ -10,7 +10,7 @@ pytest-cov==3.0.0
 pytest-sugar==0.9.7
 pytest-timeout==2.1.0
 restructuredtext-lint==1.4.0
-pygments==2.15.1
+pygments==2.16.1
 testtools>=2.4.0
 sortedcontainers~=2.4.0
 pytest-asyncio>=0.21.0