git-summary: update mapping

Note: stretch is weeks away from EOL anyway.

scripts/git-summary

@@ -9,10 +9,9 @@ use List::MoreUtils qw(all any);
 
 # What the branches mean in term of suites:
 my %branches = qw(
-  oldoldstable wheezy
-  oldstable    jessie
-  stable       stretch
-  testing      buster
+  oldstable    stretch
+  stable       buster
+  testing      bullseye
   unstable     master
 );
 my @important = qw(oldstable stable testing);