Add Ubuntu 24.04, drop 20.04 (#20)

Author: gibbs

metadata.json

@@ -44,8 +44,8 @@
     {
       "operatingsystem": "Ubuntu",
       "operatingsystemrelease": [
-        "22.04",
-        "20.04"
+        "24.04",
+        "22.04"
       ]
     },
     {

provision.yaml

@@ -6,7 +6,7 @@ default:
     - 'litmusimage/almalinux:9'
     - 'litmusimage/debian:11'
     - 'litmusimage/debian:12'
-    - 'litmusimage/ubuntu:20.04'
     - 'litmusimage/ubuntu:22.04'
+    - 'litmusimage/ubuntu:24.04'
     - 'litmusimage/rockylinux:8'
     - 'litmusimage/rockylinux:9'