find-unneeded-includes: don't propose debug/set.h if multiset is used

As seen while cleaning sd/source/ui/dlg/TemplateScanner.cxx

Change-Id: I31a6892b4419947a411b2c4100281d4cf7c50f09
Reviewed-on: https://gerrit.libreoffice.org/68969
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>

bin/find-unneeded-includes

@@ -46,6 +46,7 @@ def ignoreRemoval(include, toAdd, absFileName, moduleRules):
         "list": "debug/list",
         "map": "debug/map.h",
         "set": "debug/set.h",
+        "set": "debug/multiset.h",
         "unordered_map": "debug/unordered_map",
         "unordered_set": "debug/unordered_set",
         "vector": "debug/vector",