[BUG] [Python] Fix autoset constants Python code for default query string value

[keenangraham]

#16761 introduced Python code to set default header or query string value when OpenAPI parameter is required and has one enum value (have to use --additional-properties autosetConstants=true to activate functionality).

The Python mustache template tries to add parameter to _query_params dict, but query_params is a list:

_query_params: List[Tuple[str, str]] = []
...
# Set client side default value of Query Param "{{baseName}}".
_query_params['{{baseName}}'] = {{#_enum}}'{{{.}}}'{{/_enum}} # wrong

https://github.com/prashant-pant/openapi-generator/blob/21ee1101f5fb310904ae904018cee93d249b796d/modules/openapi-generator/src/main/resources/python/api.mustache#L196-L228

This PR updates mustache template to append query string tuple to _query_string list.

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[wing328]

thanks for the pr

CC
@cbornet (2017/09) @tomplus (2018/10) @krjakbrjak (2023/02) @fa0311 (2023/10) @multani (2023/10)

[wing328]

thanks for the PR. let's give it a try