ci: remove ubuntu 20.04, use docker 27.5 for testing

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

.github/workflows/ci.yml

@@ -9,12 +9,11 @@ jobs:
     strategy:
       matrix:
         os:
-          - ubuntu:20.04
           - ubuntu:22.04
           - ubuntu:24.04
           - quay.io/centos/centos:stream9
         version:
-          - "26.1"
+          - "27.5"
           - ""
 
     steps: