fix typo

semicolon causes an error on the shell

howto/upgrades/bookworm.md

@@ -164,7 +164,7 @@ See the "conflicts resolution" section below for how to handle
         apt clean &&
         : review and purge older kernel if the new one boots properly &&
         dpkg -l 'linux-image*' | less &&
-        ; review obsolete and odd packages &&
+        : review obsolete and odd packages &&
         apt purge '?obsolete' && apt autopurge &&
         apt list "?narrow(?installed, ?not(?codename($(lsb_release -c -s | tail -1))))" &&
         printf "End of Step 8\a\n" &&