Remove symeq

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

src/Bergamot/Rules.elm

@@ -206,10 +206,6 @@ builtinRules t =
                     case mp of
                         Nothing -> pure <| MkProofTree { name = "BuiltinNot", conclusion = t, premises = [] }
                         Just _ -> fail)
-            Call "symeq" [Call s1 [], Call s2 []] ->
-                if s1 == s2
-                then pure <| MkProofTree { name = "BuiltinSymEq", conclusion = t, premises = [] }
-                else fail
             _ -> fail
 
 provePremises : List (Term UnificationVar) -> Prover (List ProofTree)