Bump pygments from 2.6.1 to 2.7.4 in /ci_scripts

Bumps [pygments](https://github.com/pygments/pygments) from 2.6.1 to 2.7.4.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](https://github.com/pygments/pygments/compare/2.6.1...2.7.4)

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

ci_scripts/docs-requirements.txt

@@ -4,4 +4,4 @@ sphinx==2.4.4
 #FIXME: switch back to upstream sphinx-js when https://github.com/mozilla/sphinx-js/pull/135 is merged or the issue is fixed otherwise
 git+git://github.com/reuben/sphinx-js.git@a24775935443d21028ee4a7025a407c78030c4e7#egg=sphinx-js
 sphinx-rtd-theme==0.4.3
-pygments==2.6.1
+pygments==2.7.4