Support new bullseye

See https://git.vvvvvvaria.org/varia/bibliotecha-report/issues/1

bibliotecha.sh

@@ -100,22 +100,28 @@ function ensure_buster_based_distribution {
   echo "Checking distribution ..."
 
   local installing_on_buster_based=1
+  local installing_on_bullseye_based=1
 
   if [ ! -f /etc/apt/sources.list ]; then
     installing_on_buster_based=
+    installing_on_bullseye_based=
   else
     if ! grep -q 'buster' /etc/apt/sources.list; then
         installing_on_buster_based=
     fi
+    if ! grep -q 'bullseye' /etc/apt/sources.list; then
+        installing_on_bullseye_based=
+    fi
     if ! grep -q 'debian' /etc/apt/sources.list; then
         if ! grep -q 'raspbian' /etc/apt/sources.list; then
             installing_on_buster_based=
+            installing_on_bullseye_based=
         fi
     fi
   fi
 
-  if [ ! $installing_on_buster_based ]; then
+  if [ ! $installing_on_buster_based ] && [ ! $installing_on_bullseye_based ]; then
-    echo "You should only run this on a Debian Buster based system"
+    echo "This installation script only supports a Debian Buster/Bullseye based system, sorry!"
     exit 1
   fi
 }