fix: reader float parser

[iliyanm]

Description

Changed the reader float parser to support nan values.
Based on the redis documentation possible float values should be:

",inf\r\n"
",-inf\r\n"
",nan\r\n"

Example

When I execute FT.INFO *index name* parameter records_per_doc_avg can be -nan and the float parser returns:

strconv.ParseFloat: parsing "-nan": invalid syntax

[iliyanm]

@monkey92t could you please review

[monkey92t]

I don't understand why use *float64? Maybe math.Nan()?

[iliyanm]

@monkey92t you are right. I changed it, please review again.