allow arrow timestamptz with UTC to be read as iceberg timestamp

Author: kevinjqliu

pyiceberg/io/pyarrow.py

@@ -1844,11 +1844,11 @@ def _cast_if_needed(self, field: NestedField, values: pa.Array) -> pa.Array:
                         pa.types.is_timestamp(target_type)
                         and not target_type.tz
                         and pa.types.is_timestamp(values.type)
-                        and not values.type.tz
+                        and (values.type.tz in UTC_ALIASES or values.type.tz is None)
                     ):
                         if target_type.unit == "us" and values.type.unit == "ns" and self._downcast_ns_timestamp_to_us:
                             return values.cast(target_type, safe=False)
-                        elif target_type.unit == "us" and values.type.unit in {"s", "ms"}:
+                        elif target_type.unit == "us" and values.type.unit in {"s", "ms", "us"}:
                             return values.cast(target_type)
                     raise ValueError(f"Unsupported schema projection from {values.type} to {target_type}")
                 elif field.field_type == TimestamptzType():