Issue 3143: Don't duplicate text for anchors

When creating an anchor element we were adding its representation
as well as the original content, leading to text duplication.

src/Text/Pandoc/Readers/Odt/ContentReader.hs

@@ -713,8 +713,7 @@ maybeAddAnchorFrom anchorReader =
   >>>
   proc (inlines, fAnchorElem) -> do
   case fAnchorElem of
-    Right anchorElem ->
-      arr (anchorElem <>) -<< inlines
+    Right anchorElem -> returnA -< anchorElem
     Left _           -> returnA -< inlines
   where
     toAnchorElem :: Anchor -> Inlines

tests/odt/native/referenceToText.native

@@ -1 +1 @@
-[Para [Span ("an anchor",[],[]) [],Str "Some",Space,Str "text."],Para [Str "A",Space,Str "reference",Space,Str "to",Space,Link ("",[],[]) [Str "Some",Space,Str "text"] ("#an anchor",""),Str "."]]
+[Para [Span ("an anchor",[],[]) [],Str "Some",Space,Str "text."],Para [Str "A",Space,Str "reference",Space,Str "to",Space,Link ("",[],[]) [Str "Some",Space,Str "text"] ("#an anchor",""),Str "."],Para [Str "Some",Space,Str "text",LineBreak,Str "Another",Space,Str "one",Space,Str "with",Space,Str "a",Space,Str "link",Span ("anchor",[],[]) []]]