fix: remove bigint from lsr

Author: gwansikk

compiler/ml/unified_ops.ml

@@ -183,7 +183,7 @@ let entries =
           int = Plsrint;
           bool = None;
           float = None;
-          bigint = Some Pasrbigint;
+          bigint = None;
           string = None;
         };
     };

tests/tests/src/unified_ops_test.res

@@ -35,4 +35,3 @@ let shr_int = 8 >> 2
 let ushr_int = -1 >>> 1
 
 let shl_bigint = 1n << 2n
-let shr_bigint = 8n >> 2n