Bump pproxy from 2.3.5 to 2.3.7 (#212)

Bumps [pproxy](https://github.com/qwj/python-proxy) from 2.3.5 to 2.3.7.
- [Release notes](https://github.com/qwj/python-proxy/releases)
- [Commits](https://github.com/qwj/python-proxy/commits)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Florimond Manca <florimond.manca@gmail.com>
Co-authored-by: Josep Cugat <jcugat@gmail.com>

Author: 3 people

requirements.txt

@@ -23,7 +23,7 @@ flake8-bugbear==20.1.4
 flake8-pie==0.6.1
 isort==5.5.4
 mypy==0.782
-pproxy==2.3.5
+pproxy==2.3.7
 pytest==6.1.1
 pytest-trio==0.6.0
 pytest-cov==2.10.1