Bump pycountry from 19.8.18 to 20.7.3

Bumps [pycountry](https://github.com/flyingcircusio/pycountry) from 19.8.18 to 20.7.3.
- [Release notes](https://github.com/flyingcircusio/pycountry/releases)
- [Changelog](https://github.com/flyingcircusio/pycountry/blob/master/HISTORY.txt)
- [Commits](https://github.com/flyingcircusio/pycountry/compare/19.8.18...20.7.3)

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

requirements.txt

@@ -17,7 +17,7 @@ natsort==6.2.1
 ns1-python==0.16.0
 ovh==0.5.0
 pycountry-convert==0.7.2
-pycountry==19.8.18
+pycountry==20.7.3
 python-dateutil==2.8.1
 requests==2.24.0
 s3transfer==0.3.3