fix: ubuntu2004 deprecated

Author: bzp2010

.github/workflows/cli.yml

@@ -25,7 +25,7 @@ jobs:
       fail-fast: false
       matrix:
         platform:
-          - ubuntu-20.04
+          - ubuntu-latest
         job_name:
           - linux_apisix_current_luarocks
           - linux_apisix_current_luarocks_in_customed_nginx