[graph] remove the Data.Sequence quickfix

We are back to using original "sequences" package, it seems to work
OK (except the recursion error is still thrown, but that was also with
Data.Array).

spago.dhall

@@ -70,6 +70,7 @@ to generate this file without the comments in this block.
   , "record"
   , "record-extra"
   , "routing"
+  , "sequences"
   , "simple-json"
   , "simple-json-generics"
   , "simplecrypto"

src/SeqFix/DataSequence.purs

-module Data.Sequence where
+module Data.SequenceArr where
 
 import Prelude
 import Data.Array as A
@@ -27,4 +27,3 @@ singleton = A.singleton
 splitAt idx seq = Tuple s.before s.after
   where
     s = A.splitAt idx seq
-