fix: parse float to string with precision to a sufficient level

[judehung]

fixes #989

The original implemetation uses fmt.Sprintf("%e", value) to convert float to string, which will be truncated and rounded at the 6th decimal point. For a float value that needs more precision (not arbitrary precision), it's better to use strconv.FormatFloat with prec -1 to achieve the smallest number of digits necessary such that ParseFloat will return f exactly. Moreover, as fmt.Sprintf is for more general purpose and strconv.FormatFloat is specifically for formatting a float, the strconv.FormatFloat has better performance than fmt.Sprintf.

The benchmark test shows the strconv.FormatFloat takes 955.5 ns/op and fmt.Sprintf takes 1961 ns/op.

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PR Checklist

Please check if your PR fulfills the following requirements:

• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
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• I have fully tested (add details below) this the new feature or bug fix (if not, why?)
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Testing Instructions

I only run make unittest to verify if any unit tests breaks.

New Dependency Instructions (If applicable)

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Codecov Report

Attention: Patch coverage is 53.84615% with 6 lines in your changes missing coverage. Please review.

Project coverage is 42.95%. Comparing base (de36d96) to head (37c58d2).

Files with missing lines	Patch %	Lines
dtos/reading.go	53.84%	4 Missing and 2 partials ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #994      +/-   ##
==========================================
+ Coverage   42.93%   42.95%   +0.01%     
==========================================
  Files         119      119              
  Lines        7208     7220      +12     
==========================================
+ Hits         3095     3101       +6     
- Misses       3770     3774       +4     
- Partials      343      345       +2     

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[cloudxxx8]

LGTM