Use correct docker version in main.yml

.github/workflows/main.yml

@@ -29,7 +29,7 @@ jobs:
       run: docker --version
     - name: Install Latest Docker
       run: |
-          curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
+          curl -fsSL https://apt.dockerproject.org/gpg | apt-key add -
           sudo apt-add-repository "deb https://apt.dockerproject.org/repo ubuntu-$(lsb_release -cs) main"        
           sudo apt-get update -y && apt-get install docker-ce=18.06.2~ce~3-0~ubuntu
     - name: Check Docker Version