Add diameter exclusions to xref

rebar.config

@@ -15,5 +15,8 @@
       - (\"erlydtl\":\"compile\"/\"3\")
       - (\"lfe_comp\":\"file\"/\"2\")
       - (\"neotoma\":\"file\"/\"2\")
-      - (\"protobuffs_compile\":\"scan_file\"/\"2\"))",
+      - (\"protobuffs_compile\":\"scan_file\"/\"2\")
+      - (\"diameter_codegen\":\"from_dict\"/\"4\")
+      - (\"diameter_dict_util\":\"format_error\"/\"1\")
+      - (\"diameter_dict_util\":\"parse\"/\"2\"))",
          []}]}.