Add missing import in crossref filter

It has its own loading different than main.lua one.

Author: cderv

src/resources/filters/crossref/crossref.lua

@@ -61,6 +61,7 @@ import("../quarto-init/resourcerefs.lua")
 
 import("../normalize/flags.lua")
 import("../normalize/normalize.lua")
+import("../normalize/pandoc-tables.lua")
 import("../normalize/parsehtml.lua")
 import("../normalize/extractquartodom.lua")
 import("../normalize/astpipeline.lua")