Bump docker from 4.2.2 to 4.3.0

Bumps [docker](https://github.com/docker/docker-py) from 4.2.2 to 4.3.0.
- [Release notes](https://github.com/docker/docker-py/releases)
- [Commits](https://github.com/docker/docker-py/compare/4.2.2...4.3.0)

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

requirements.txt

@@ -4,7 +4,7 @@ certifi==2020.6.20
 chardet==3.0.4
 colorama==0.4.3; sys_platform == 'win32'
 distro==1.5.0
-docker==4.2.2
+docker==4.3.0
 docker-pycreds==0.4.0
 dockerpty==0.4.1
 docopt==0.6.2