Bump requests from 2.17.3 to 2.20.0

Bumps [requests](https://github.com/psf/requests) from 2.17.3 to 2.20.0.
- [Release notes](https://github.com/psf/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/master/HISTORY.md)
- [Commits](psf/requests@v2.17.3...v2.20.0)

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

requirements.txt

@@ -7,6 +7,6 @@ idna==2.5
 PyQt5==5.8.2
 pytz==2017.2
 Quamash==0.5.5
-requests==2.17.3
+requests==2.20.0
 sip==4.19.2
 urllib3==1.21.1