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]

requirements.txt

@@ -59,7 +59,7 @@ pyyaml==3.12              # via datapackage-pipelines
 readchar==2.0.1           # via inquirer
 redis==2.10.6             # via datapackage-pipelines, os-api-cache
 regex==2017.9.23          # via awesome-slugify
-requests==2.18.4          # via datapackage, datapackage-pipelines, tableschema, tabulator
+requests==2.20.0          # via datapackage, datapackage-pipelines, tableschema, tabulator
 rfc3986==1.1.0            # via tableschema
 s3transfer==0.1.13        # via boto3
 six==1.11.0               # via blessings, datapackage, datapackage-pipelines-fiscal, flask-cors, isodate, jsonlines, linear-tsv, python-dateutil, tableschema, tableschema-sql, tabulator