[skip-ci] Remove EOL operatingsystems

Author: ekohl

metadata.json

@@ -23,16 +23,13 @@
     {
       "operatingsystem": "CentOS",
       "operatingsystemrelease": [
-        "5",
         "6",
         "7"
       ]
     },
     {
       "operatingsystem": "Debian",
       "operatingsystemrelease": [
-        "6",
-        "7",
         "8"
       ]
     }