Use ubuntu-20.04 as cannot get previous version of docker

.github/workflows/main.yml

@@ -11,7 +11,7 @@ on:
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     steps:
     - uses: actions/checkout@v2
@@ -25,16 +25,6 @@ jobs:
       run: echo GO_USR_DIRS=$(go list -f {{.Dir}} ./... | grep -E -v "/gen-go/|/vendor/") >> $GITHUB_ENV
     - name: Run goimports check
       run: test -z "`for d in $GO_USR_DIRS; do goimports -d $d/*.go | tee /dev/stderr; done`"
-    - name: Check Docker Version
-      run: docker --version
-    - name: Install Latest Docker
-      run: |
-        curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
-        sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu  $(lsb_release -cs)  stable"
-        sudo apt-get update -y && sudo apt-get install docker-ce=18.06.3~ce~3-0~ubuntu_amd64.deb
-    - name: Check Docker Version
-      run: docker --version
-
     - name: Create aurora/mesos docker cluster
       run: docker-compose up -d
     - name: Run tests