Merge pull request #702 from StatensPensjonskasse/add-el8-and-debian11

add redhat8, centos8  and debian11 support

Author: h-haaks

metadata.json

@@ -11,19 +11,22 @@
     {
       "operatingsystem": "RedHat",
       "operatingsystemrelease": [
-        "7"
+        "7",
+        "8"
       ]
     },
     {
       "operatingsystem": "CentOS",
       "operatingsystemrelease": [
-        "7"
+        "7",
+        "8"
       ]
     },
     {
       "operatingsystem": "Debian",
       "operatingsystemrelease": [
-        "10"
+        "10",
+        "11"
       ]
     },
     {