Update ubuntu version in azure pipeline (sonic-net#572)

Author: vvolam

azure-pipelines.yml

@@ -19,7 +19,7 @@ variables:
 
 
 pool:
-  vmImage: 'ubuntu-20.04'
+  vmImage: 'ubuntu-24.04'
 
 container:
   image: sonicdev-microsoft.azurecr.io:443/sonic-slave-bookworm:latest