SELECT SUM(*) does unwanted type cast

[SBrandeis]

Software versions

Influxdb version: 1.7.6
influxdb-python version: 5.2.2

Steps to reproduce:

1. Create a measurement named my_measurement in influxdb with following points:

time         data_type   value
----------   ----------  -----
15578637...   Num         12.5
15578637...   Num         12.5

2. Run the following code:

>>> from influxdb import InfluxDBClient

>>> c = InfluxDBClient(...)

>>> result_set = c.query('select * from my_measurement')
... for _, generator in result_set.items():
...     for point in generator:
...         print(type(point['value']))
<class 'float'>
<class 'float'>

>>> result_set = c.query('select sum(*) from my_measurement')
... for _, generator in result_set.items():
...     for point in generator:
...         print(type(point['sum_value']))
<class 'int'>

The casting into 'int' type is incorrect since we are summing floats, result should still be a float.

[lovasoa]

See the issue in influxsb itself: influxdata/influxdb#8707
The solution they recommend is using messagepack, which I implemented in #734.

[aviau]

this wasn't an influxdb-python issue anyways afaik