add buildx plugin

scripts/travis-setup.sh

@@ -22,6 +22,10 @@ sudo apt-get -y -o Dpkg::Options::="--force-confnew" install docker-ce
 curl -LO https://storage.googleapis.com/container-diff/latest/container-diff-linux-amd64 && chmod +x container-diff-linux-amd64 && sudo mv container-diff-linux-amd64 /usr/local/bin/container-diff
 docker run -d -p 5000:5000 --restart always --name registry registry:2
 
+mkdir -vp ~/.docker/cli-plugins/
+curl --silent -L "https://github.com/docker/buildx/releases/download/v0.3.0/buildx-v0.3.0.linux-amd64" > ~/.docker/cli-plugins/docker-buildx
+chmod a+x ~/.docker/cli-plugins/docker-buildx
+docker buildx version
 docker buildx create --use --platform=linux/amd64
 
 mkdir -p $HOME/.docker/