Set Ubuntu to 20.04 in CI (#4285)

Signed-off-by: Gábor Lipták <[email protected]>

Author: gliptak

.github/workflows/test-build-deploy.yml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   lint:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     container:
       image: quay.io/cortexproject/build-image:build-image-multiarch-1d2497ff6
     steps:
@@ -32,7 +32,7 @@ jobs:
         run: make BUILD_IN_CONTAINER=false check-white-noise
 
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     container:
       image: quay.io/cortexproject/build-image:build-image-multiarch-1d2497ff6
     services:
@@ -53,7 +53,7 @@ jobs:
         run: CASSANDRA_TEST_ADDRESSES=cassandra:9042 make BUILD_IN_CONTAINER=false test
 
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     container:
       image: quay.io/cortexproject/build-image:build-image-multiarch-1d2497ff6
     steps:
@@ -93,7 +93,7 @@ jobs:
 
   integration:
     needs: build
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-20.04
     steps:
       - name: Upgrade golang
         run: |
@@ -157,7 +157,7 @@ jobs:
 
   integration-configs-db:
     needs: build
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-20.04
     steps:
       - name: Checkout Repo
         uses: actions/checkout@v2
@@ -179,7 +179,7 @@ jobs:
   deploy_website:
     needs: [build, test]
     if: (github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/tags/')) && github.repository == 'cortexproject/cortex'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     container:
       image: quay.io/cortexproject/build-image:build-image-multiarch-1d2497ff6
     steps:
@@ -216,7 +216,7 @@ jobs:
   deploy:
     needs: [build, test, lint, integration, integration-configs-db]
     if: (github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/tags/')) && github.repository == 'cortexproject/cortex'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     container:
       image: quay.io/cortexproject/build-image:build-image-multiarch-1d2497ff6
     steps: