Fix: converting string into integers and rationals

[carlos-adir]

As described by #5, the actual behaviour is:

>>> from rbool import *
>>> from_any("{-5, 3}")
{-5.0, 3.0}

This PR sets to:

>>> from_any("{-5, 3/7}")
{-5, 3/7}

The first one is transformed to integer, while the second is to fractions

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.84%. Comparing base (820526e) to head (1d2da9e).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main       #6   +/-   ##
=======================================
  Coverage   99.84%   99.84%           
=======================================
  Files           9        9           
  Lines         650      660   +10     
=======================================
+ Hits          649      659   +10     
  Misses          1        1           

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