Bump requests from 2.18.4 to 2.20.0

Bumps [requests](https://github.com/requests/requests) from 2.18.4 to 2.20.0.
- [Release notes](https://github.com/requests/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/master/HISTORY.md)
- [Commits](psf/requests@v2.18.4...v2.20.0)

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

Author: dependabot[bot]

setup.py

@@ -13,7 +13,7 @@
       install_requires=[
           'singer-python>=5.1.0,<5.2.0',
           'backoff==1.3.2',
-          'requests==2.18.4',
+          'requests==2.20.0',
           'requests-oauthlib==0.8.0',
           'funcy==1.10.1',
       ],