Bump pudb from 2015.4.1 to 2018.1

Bumps [pudb](https://github.com/inducer/pudb) from 2015.4.1 to 2018.1.
- [Release notes](https://github.com/inducer/pudb/releases)
- [Commits](inducer/pudb@v2015.4.1...v2018.1)

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

Author: dependabot-support

requirements-dev.txt

@@ -2,4 +2,4 @@ flake8==3.5.0
 pytest==3.5.0
 pytest-asyncio==0.8.0
 pytest-cov==2.5.1
-pudb==2015.4.1
+pudb==2018.1