build(deps): bump proto-plus from 1.20.0 to 1.20.1

Bumps [proto-plus](https://github.com/googleapis/proto-plus-python) from 1.20.0 to 1.20.1.
- [Release notes](https://github.com/googleapis/proto-plus-python/releases)
- [Changelog](https://github.com/googleapis/proto-plus-python/blob/main/CHANGELOG.md)
- [Commits](googleapis/proto-plus-python@v1.20.0...v1.20.1)

---
updated-dependencies:
- dependency-name: proto-plus
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements.txt

@@ -57,7 +57,7 @@ packaging==21.3
 pbr==5.8.1
 praw==7.5.0
 prawcore==2.3.0
-proto-plus==1.20.0
+proto-plus==1.20.1
 protobuf==3.19.4
 pyasn1==0.4.8
 pyasn1-modules==0.2.8