Enable running on Debian Bullseye

Some adaption in database handling is all that is missing. Also add a
platform job that tests this.

Co-Authored-By: Radosław Piliszek <radoslaw.piliszek@gmail.com>
Change-Id: I6dd3e48444dd415d84df5e7f5c74540847cdd6db
diff --git a/stack.sh b/stack.sh
index 48f61fb..8a8e3ea 100755
--- a/stack.sh
+++ b/stack.sh
@@ -227,7 +227,7 @@
 
 # Warn users who aren't on an explicitly supported distro, but allow them to
 # override check and attempt installation with ``FORCE=yes ./stack``
-SUPPORTED_DISTROS="focal|f34|opensuse-15.2|opensuse-tumbleweed|rhel8"
+SUPPORTED_DISTROS="bullseye|focal|f34|opensuse-15.2|opensuse-tumbleweed|rhel8"
 
 if [[ ! ${DISTRO} =~ $SUPPORTED_DISTROS ]]; then
     echo "WARNING: this script has not been tested on $DISTRO"