Merge pull request #1213 from zilchms/ubuntu18

Drop Ubuntu 18.04 support

Author: h-haaks

metadata.json

@@ -64,7 +64,6 @@
     {
       "operatingsystem": "Ubuntu",
       "operatingsystemrelease": [
-        "18.04",
         "20.04",
         "22.04"
       ]