[Buildroot] [git commit branch/2020.02.x] packager/docker-cli: bump version to 19.03.7

commit: https://git.buildroot.net/buildroot/commit/?id=32ad7463e80624433e2193e9599ba0ca1da25d93
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2020.02.x

To match the docker-engine version.

./support/testing/run-tests tests.package.test_docker_compose.TestDockerCompose
09:54:39 TestDockerCompose                        Starting
09:54:40 TestDockerCompose                        Building
10:45:33 TestDockerCompose                        Building done
10:46:30 TestDockerCompose                        Cleaning up