use newer ubuntu for old varnish

Author: dbu

.github/workflows/ci.yml

@@ -95,7 +95,7 @@ jobs:
 
   varnish5:
     name: PHP ${{ matrix.php }} Legacy Varnish 5
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     env:
       VARNISH_VERSION: '5.1'
       VARNISH_MODULES_VERSION: '0.14.0'
@@ -132,7 +132,7 @@ jobs:
 
   varnish4:
     name: PHP ${{ matrix.php }} Legacy Varnish 4
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     env:
       VARNISH_VERSION: '4.1'
       VARNISH_MODULES_VERSION: '' # varnish modules compilation fails, not sure why

.github/workflows/setup-varnish-legacy.sh

@@ -2,6 +2,7 @@
 
 set -e
 echo "### Installing Legacy Varnish $VARNISH_VERSION ###"
+sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) universe"
 sudo apt-get update
 sudo apt-get install debian-archive-keyring curl gnupg apt-transport-https
 VARNISH_VERSION=$VARNISH_VERSION bash -c 'curl -s -L https://packagecloud.io/varnishcache/varnish${VARNISH_VERSION//./}/gpgkey' | sudo apt-key add -