fix: enhance utf8_literal function to handle non-string values

Author: kosiew

python/datafusion/expr.py

@@ -383,8 +383,10 @@ def literal(value: Any) -> Expr:
     @staticmethod
     def utf8_literal(value: str) -> Expr:
         """Creates a new expression representing a UTF8 literal value."""
-        value = pa.scalar(value, type=pa.string())
-        return Expr(expr_internal.Expr.literal(value))
+        if isinstance(value, str):
+            value = pa.scalar(value, type=pa.string())
+            return Expr(expr_internal.Expr.literal(value))
+        return literal(value)
 
     @staticmethod
     def column(value: str) -> Expr: