Tests: fix slider tests failing on certain cultures

[henon]

Two slider tests failed on my locale. Made sure they work everywhere the same.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.46%. Comparing base (28bc599) to head (da374a9).
Report is 186 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #8949      +/-   ##
==========================================
+ Coverage   89.82%   90.46%   +0.63%     
==========================================
  Files         412      419       +7     
  Lines       11878    12197     +319     
  Branches     2364     2381      +17     
==========================================
+ Hits        10670    11034     +364     
+ Misses        681      628      -53     
- Partials      527      535       +8     

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[ScarletKuro]

Should we maybe just set [SetCulture("en-US")] on the tests to not rely on the converters that might be reworked in future?

[henon]

I don't mind for the tests, will change.

But even if the converters are reworked they will do exactly this job, converting to and from string using a specified culture.