Bump pycparser from 2.20 to 2.21

Bumps [pycparser](https://github.com/eliben/pycparser) from 2.20 to 2.21.
- [Release notes](https://github.com/eliben/pycparser/releases)
- [Changelog](https://github.com/eliben/pycparser/blob/master/CHANGES)
- [Commits](eliben/pycparser@release_v2.20...release_v2.21)

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

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

Author: dependabot[bot]

requirements.txt

@@ -32,7 +32,7 @@ multidict==5.2.0
     #   yarl
 pycares==4.1.2
     # via aiodns
-pycparser==2.20
+pycparser==2.21
     # via cffi
 pygments==2.10.0
     # via rich