fix: add pdf annotation to private tags

deps/db/src/logseq/db/frontend/class.cljs

@@ -114,7 +114,8 @@
   "Built-in classes that are private and should not be used by a user directly.
   These used to be in block/type"
   (set/union (disj internal-tags :logseq.class/Root)
-             #{:logseq.class/Journal :logseq.class/Whiteboard}))
+             #{:logseq.class/Journal :logseq.class/Whiteboard
+               :logseq.class/Pdf-annotation}))
 
 (def extends-hidden-tags
   "Built-in classes that are hidden when choosing extends"