fetch_dataframe returning float types incorrectly

The **fetch_dataframe** method provided by the Redshift connector appears to return more decimal places than expected. For example, 0.074 becomes 0.07400000095367, likely due to how Redshift stores and retrieves floating-point or decimal values with higher precision than originally intended.

The first image shows what was returned by the **fetch_dataframe** method and although the revenue growth column is exactly what we expected (exact user inputs without more decimal places), when we actually take a look at one of the values specifically (second one in this case), we get the value in the second image. This suggests that fetch_dataframe is already returning extra decimal places but just not viewable when printing the whole dataframe. For now, we have identified that this is a problem for the datatypes **REAL** and **DOUBLE PRECISION** on the redshift connector.

首先追蹤 fetch_dataframe 方法，並在 Redshift 中重現 REAL 和 DOUBLE PRECISION 的回報值。將回傳值與輸入精度及現有 connector 行為進行比較；當回傳預期的小數值且不包含非預期的浮點數字，並且有一個涵蓋這兩種類型的回歸測試時，即表示完成。

由索引模型根據 Issue 內容生成。