Add support for ubuntu 20.04

manifest

@@ -1,6 +1,6 @@
 #!/bin/sh
 #
-# 2013-2019 ungleich glarus ag (cdist at ungleich.ch)
+# 2013-2020 ungleich glarus ag (cdist at ungleich.ch)
 #
 # This file is part of cdist.
 #
@@ -24,6 +24,10 @@ os=$(cat $__global/explorer/os)
 osversion=$(cat "$__global/explorer/os_version")
 
 case "$os" in
+    alpine)
+        postgres_lib="postgresql-dev"
+        postgres_server="postgresql"
+    ;;
     debian|devuan)
         postgres_lib=libpq-dev
 
@@ -57,10 +61,22 @@ case "$os" in
         postgres_server="postgresql-${postgres_version}"
 
     ;;
-    alpine)
-        postgres_lib="postgresql-dev"
-        postgres_server="postgresql"
+    ubuntu)
+        postgres_lib=libpq-dev
+
+        case $osversion in
+            20.04)
+                postgres_version=12
                 ;;
+            *)
+                echo "Unsupported OS Version: $osversion" >&2
+                exit 1
+            ;;
+        esac
+        postgres_server="postgresql-${postgres_version}"
+
+        ;;
+
     *)
         echo "Unsupported OS: $os" >&2
         exit 1