Pandas outputs warning when calling dataframe.append in flux_csv_parser._prepare_data_frame

### Specifications

* Client Version: 1.36.0
* InfluxDB Version: 2.7

### Code sample to reproduce problem

```python
query_api.query_data_frame(query)
```

### Expected behavior

The query should be executed without warnings.

### Actual behavior

Pandas outputs a FutureWarning:

```
/usr/local/lib/python3.11/site-packages/influxdb_client/client/flux_csv_parser.py:256: FutureWarning:
The behavior of array concatenation with empty entries is deprecated. In a future version, this will no longer exclude empty items when determining the result dtype. To retain the old behavior, exclude the empty entries before the concat operation.
```

This is related to the this code snippet:

https://github.com/influxdata/influxdb-client-python/blob/aa6e5c4aad1aaf004195c175ebe424ac6040c2e3/influxdb_client/client/flux_csv_parser.py#L243C9-L256

### Additional info

In the recent pandas version handling of concatenation of empty dataframes changed, see https://github.com/pandas-dev/pandas/issues/39122. This should be handled else wise to reflect the changes in pandas.

influxdb_client/client/flux_csv_parser.py の243-256行付近で、query_data_frame が dataframe を構築している箇所から始め、query_api.query_data_frame(query) で警告を再現してください。pandas issue 39122 で説明されている pandas の連結に関する変更と動作を比較してください。query が報告された FutureWarning なしで実行されれば完了です。

索引モデルが issue の本文から書いたものです。